Turkish Prime Minister Recep Tayyip Erdogan, right, arrives at a conference hall as Stefan Fule, left, the EU enlargement commissioner smiles, in Istanbul on Friday, June 7, 2013. Fule on Friday criticized Turkish police's harsh crackdown on protesters told an audience including Erdogan that a "swift and transparent" investigation was needed. A protester holding a Turkish flag and a book with the image of Turkey's founder Mustafa Kemal Ataturk, arrives for Friday prayers at Gezi Park near Taksim Square in Istanbul, Friday, June 7, 2013. Stefan Fule, the European Union enlargement commissioner delivers a speech during a conference in Istanbul on Friday, June 7, 2013. Fule on Friday criticized Turkish police's harsh crackdown on protesters told an audience including Turkish Prime Minister Recep Tayyip Erdogan that a "swift and transparent" investigation was needed. Turkish Prime Minister Recep Tayyip Erdogan delivers a speech during a conference in Istanbul on Friday, June 7, 2013. A senior European Union official on Friday criticized Turkish police's harsh crackdown on protesters told an audience including Erdogan that a "swift and transparent" investigation was needed. Muslims attend Friday prayers outside a mosque near Taksim Square in Istanbul, Friday June 7, 2013. ISTANBUL (AP) - A violent police crackdown on a small environmental sit-in at Istanbul's central Taksim Square has done more than spawn a week of protests across the country. It has left cracks in the shiny international image of a tolerant and deeply democratic Turkey. It might even have rattled the nation's grand ambitions on the world stage, which include a bid to host the 2020 Olympics and its long-standing aim to join the European Union. Thousands of protesters gathered for the eighth consecutive night Friday in Istanbul's Taksim Square, where the demonstrations originally began, and about 10,000 showed up at the main square in the capital, Ankara. They are venting anger at Prime Minister Reccep Tayyip Erdogan, who has said the protests are bordering on illegality and must stop immediately. In his decade in power, Erdogan has been the driving force behind many of the reforms essential to push Turkey's EU bid forward, including significant improvements to human rights legislation. The country's economy has blossomed and infrastructure projects have burgeoned, especially in Istanbul. But many say he's gone too far. Dissent is rarely tolerated and some outspoken critics, including journalists and politicians, have been jailed. Now critics and even some supporters, accuse the prime minister of ignoring the fears and concerns of the 50 percent of the electorate who did not vote for him. "Turkey has been harmed in many ways in the last ten day in terms of the image (and) financial markets," said Cengiz Aktar, professor of international relations of Bahcesehir University. The main index on the Istanbul Stock Exchange fell by 8 percent Thursday, after Erdogan made statements in Tunisia during a North Africa trip saying that the development project for Taksim Square would go ahead. It recouped some of its losses Friday, but has lost about 9 percent in a week. There is only one, just one person who can solve this problem and his name is Erdogan. We are all watching his lips," Aktar said. On his return to Istanbul early Friday, Erdogan was greeted by thousands of chanting supporters at the airport. He made a fiery speech in which he insisted he was mindful of the wishes of the entire population and not just his own supporters, but also insisted terrorists and a banking conspiracy were involved in the protests. The messages he gave last night were very concerning, and the mounted troops that were brought there, their slogans were really worrisome. These are indicating that this problem isn't going to be solved by dialogue," Aktar added. The tarnishing of Turkey's international reputation was evident during a Friday conference in Istanbul aimed at furthering the country's decades-long EU accession hopes. "The duty of all of us, European Union members as much as those countries that wish to become one, is to aspire to the highest possible democratic standards and practices," said EU Enlargement Commissioner Stefan Fule. These include the freedom to express one's opinion, the freedom to assemble peacefully and freedom of media to report on what is happening as it is happening. Democracies, he told an audience that included Erdogan, must heed the needs of the whole of society, including those who disagree with the government. Peaceful demonstrations constitute a legitimate way for these groups to express their views in a democratic society. Excessive use of force by police against these demonstrations has no place in such a democracy," he said. Erdogan retorted that the EU had human rights issues too. Turkey remained committed to joining the EU, he said, but he criticized the European bloc for the lack of progress in membership talks, saying public support for the country's accession has plummeted to 30 percent. Why is our membership advancing at such a slow pace? The people have a right to know! Erdogan said. We are determined to advance on the path of the EU, but it is not possible for Turkey to continue with one-sided efforts. There are also concerns over whether the events have damaged Istanbul's bid to host the Olympics. It has trumpeted the country's strong economy, secular democracy and geographical location linking Asia and Europe. But the images of riot police firing water cannons and massive amounts of tear gas at protesters in the center of the city could deal a blow, especially since the initial action on May 31 was against a small number of protesters who had been camping peacefully in Taksim. "As Istanbul's mayor going through such an event, the fact that the whole world watched saddens me," Hurriyet Daily News cited Istanbul Mayor Kadi Topbas as saying the following day in a television interview. How will we explain it? With what claims will we host the 2020 Olympic Games? The protesters in Taksim were objecting to Erdogan's plans to revamp the area by uprooting the trees and building a replica Ottoman-era barracks, and, initially, a shopping mall. The mall plan has since seemed to fall away, with Erdogan now referring to an opera house, theater and possibly a museum. Erdogan has acknowledged that excessive police force was used, but the prime minister also insisted tear gas is used in many countries to combat demonstrations. But the recent protests could in fact augur well for Turkey's EU bid, demonstrating the emergence of a "pluralist and mature" class in Turkish society. "This will have a very positive effect (on the EU bid) in the long run," said Ali Tekin, a professor at Yasar University in Izmir, western Turkey. In the past Turkish youths used to rely on the military to provide the checks and balances. Now they are taking it into their hands. The military has been the traditional keeper of the secular legacy of modern Turkey's founding father, Mustafa Kemal Ataturk. It has seized power three times since the early 1970s when it felt that was threatened. "Europe can see a generation of protesters who think like them and have the same ideals as them," Tekin said. These people believe in pluralism, in an inclusive democracy. ... They reject being told what to do. And this is important for the EU process. Ezgi Agin contributed from Ankara.