European Commission President Jose Manuel Barroso met China's Premier Wen Jiabao Thursday at the start of a three-day visit, with Greece's debt crisis threatening to overshadow the talks. Barroso, accompanied by several top commission officials, and Wen were expected to discuss the global financial crisis, climate change and international security issues, EU and Chinese officials said. 'We will seize this opportunity to generate positive momentum in our 35-year relationship and develop a far-reaching agenda for the next five years,' a commission statement quoted Barroso as saying ahead of the visit. 'The EU and China are important global players and it is essential that we work together in addressing common challenges.' But Barroso's visit comes as Greece battles to solve its debt problems, with Prime Minister George Papandreou calling for a 'common effort' from the EU and eurozone to prevent world economies from being dragged into a new crisis. 'In my mind there is no doubt that Greece's needs will be met in time,' Barroso told a news conference following an EU-Japan summit in Tokyo on Wednesday, adding that a Greek default was 'not an option.' 'The member states, Commission and European Central Bank are determined to guarantee the financial stability of the euro area,' he said. European leaders are planning an emergency summit on the Greek crisis on around May 10, as the head of the International Monetary Fund, Dominique Strauss-Kahn, warned confidence in the 16-nation euro area was now at stake. Germany has come under huge pressure to agree to a multi-billion-euro joint EU- IMF bailout for Greece, with Berlin providing the biggest single share of the loans. In Beijing, Barroso and other EU commissioners were also expected to touch on the Iranian nuclear issue and step up pressure on China to allow the appreciation of its currency, the yuan. 'Iran is at the top of the agenda,' an EU diplomat said in Luxembourg earlier this week. The United States, Europe and others fear Tehran is seeking the technology to build nuclear weapons, while the authorities in Iran insist that their atomic programme is purely for civilian energy use. Western nations are calling for a fresh round of UN sanctions, but Beijing -- a veto-wielding permanent member of the UN Security Council -- has so far resisted such a move. 'The Chinese haven't supported the idea of fresh sanctions but they have allowed the process to move forward,' the diplomat said. Barroso and his delegation will also attend the opening of the Shanghai Expo this weekend. 