Myanmar president holds landmark talks with rebels YANGON (Reuters) - Myanmar's president had a landmark meeting on Saturday with one of the country's biggest ethnic rebel groups, a mediator said, marking one of the biggest steps taken by a government seeking "everlasting peace" after decades of hostilities. Thein Sein, a former infantry commander and heavyweight in the junta that ceded power a year ago, told a visiting delegation of the Karen National Union (KNU) that his government viewed the rebels as brothers rather than enemy with whom the army had fought since 1949. The meeting in the capital Naypyitaw was the first time the reform-minded president had met rebel leaders since he issued a call for dialogue last August, embarking on a three-phase peace process with more than a dozen groups aimed at bringing them into Myanmar's new political system. "The president explained his change of attitude towards ethnic armed groups," a mediator who attended the meeting told Reuters by telephone, requesting anonymity because he was not authorized to talk to the media. He told them he considered ethnic armed groups as enemies when he was a soldier but after becoming president, he considers them as ethnic brethren. Peace with the militias has been demanded by Western nations now reviewing economic and political sanctions. Thein Sein's meeting comes after an historic by-election on Sunday won by opposition leader Aung San Suu Kyi's party. The international community appears to have recognized the polls as free and fair and several governments have hinted strongly that some sanctions could be lifted this month. The former regime's suppression of ethnic minorities and allegations of human rights violations by troops were a key factor in imposing the embargoes. The peace process is one of the most ambitious plans by a quasi-civilian government dominated by retired generals of the authoritarian regime who were despised by most Burmese and regarded by the West as pariahs. The new administration has embarked on a wave of social, political and economic reforms that it says are "irreversible" as it seeks to get sanctions lifted to allow a flood of foreign investment into one of Asia's last remaining frontier markets. Government negotiators started political talks with the KNU in Yangon on Friday, marking the beginning of second stage of the process, which is expected to focus on how the groups can enter national politics while maintaining some kind of self-governance at regional level. Two state negotiating groups have reached ceasefire agreements - stage one - with about a dozen armies or ethnic-based political groups so far. The mediator attending Thein Sein's meeting on Saturday said the 66-year-old president had indicated the constitution could be amended to give all groups political representation. "The weapons held in their hands should not be for fighting each other but for defending the country," he quoted Thein Sein as telling the KNU. The president said that all provisions in the constitution can be amended if all nationalities are united. Reporting by Aung Hla Tun; Writing by Martin Petty; Editing by Nick Macfie