YANGON  - Democracy champion Aung San Suu Kyi's party won almost all the seats it contested in Myanmar elections, becoming the main opposition force in the national parliament, official results showed Tuesday.

The veteran dissident's National League for Democracy stormed to victory in 43 of the 44 constituencies where it fielded candidates in Sunday's polls, according to an election commission announcement on state television. The landslide win in the by-elections gave Suu Kyi her first-ever seat in parliament, although it will not threaten the comfortable majority of the military-backed USD Party. She said  on Monday that she hoped the vote would mark a "new era" for the nation after decades of repressive junta rule, but appealed for political unity and urged her supporters not to gloat.

The NLD won 37 seats in the 440-seat lower house, along with four in the upper house and two in the regional chambers, the results showed.

One quarter of the seats are reserved for unelected military officials.

The NLD lost one seat in eastern Shan state to the Shan Nationalities Democratic Party, which has strong support among ethnic minorities.

The USDP took just one seat, in a constituency in northwest Sagaing where the NLD candidate was disqualified from standing.

Suu Kyi's election to political office marks the latest sweeping change in the country formerly known as Burma after decades of outright military rule ended last year.

Myanmar's quasi-civilian government has surprised even its critics over the past year with a string of reforms such as releasing hundreds of political prisoners and welcoming the opposition back into mainstream politics.

President Thein Sein hailed the polls as a success.

"The election was held successfully," the former general said in brief remarks to reporters on the sidelines of a meeting with fellow leaders of the Association of Southeast Asian Nations in Phnom Penh.

Observers say the regime needs Suu Kyi in parliament to bolster the legitimacy of its political system and spur an easing of Western sanctions.

The European Union opened a debate Tuesday on how fast to lift sanctions, with some EU states pushing for a "gradual, step-by-step" approach to ensure the regime continues pursuing reforms following the landmark vote.