Pro-democracy leader Aung San Suu Kyi on Monday hailed a "new era" for Myanmar and called for a show of political unity after her party claimed victory in elections seen as a test of budding reforms.
Suu Kyi supporters celebrated into the night after her National League for Democracy (NLD) party declared that the Nobel laureate had secured a seat in parliament for the first time in Sunday's by-elections.
The veteran activist's election to political office, if confirmed, would mark the latest dramatic change in the country formerly known as Burma after decades of outright military rule ended in 2011.
"This is not so much our triumph as a triumph for people who have decided that they must be involved in the political process in this country," Suu Kyi said in a victory speech at her party headquarters in Yangon.
"We hope this will be the beginning of a new era," said the activist, who was locked up by the former junta for most of the past 22 years.
Suu Kyi struck a conciliatory tone towards the other political parties as she prepares to take her place in a parliament that will remain dominated by the military and its political allies.
"We hope that all parties that took part in the elections will be in a position to cooperate with us in order to create a genuinely democratic atmosphere in our nation," she said.
The NLD said that it had won almost all of the seats it contested, based on its own tally. No official results have yet been announced.
"We won 43 seats out of 44. We are waiting for the results for the last one, in northern Shan state," said party spokesman Kyi Toe.
As a lawmaker and opposition leader in parliament, Suu Kyi would have an unprecedented voice in the legislative process, and her party is also already looking ahead to the next general election in 2015.
"Obviously they want to win the next election comprehensively and be able to set up a government in their own right," said Trevor Wilson, a Myanmar expert at the Australian National University.
Observers say the quasi-civilian government that took power a year ago needs Suu Kyi to take a place in parliament to bolster the legitimacy of its political system and spur an easing of Western sanctions.
US Secretary of State Hillary Clinton said Washington was committed to supporting the nascent reforms in Myanmar that have been cautiously welcomed by the West.
"While the results have not yet been announced, the United States congratulates the people who participated, many for their first time in the campaign and election process," Clinton said in Istanbul.
The Myanmar government has surprised even its critics over the past year with a string of reforms such as releasing hundreds of political prisoners, but ethnic conflict and alleged rights abuses remain concerns for the West.
Unlike in 2010 general elections, the government allowed foreign observers and journalists to witness Sunday's polls, which were to replace MPs who gave up their seats to join the government.
Malgorzata Wasilewska, a European Union election observer, hailed "very encouraging" signs at the roughly dozen polling stations her team visited.
"However, that's definitely not enough to assume that it is indicative of how the process was conducted in other parts of the country and certainly not enough to talk about credibility of elections," she said.
In the run-up to the eagerly awaited vote, the NLD decried alleged intimidation of candidates and other irregularities, and Suu Kyi said the poll could not be considered "a genuinely free and fair election".
The 2010 election, won by the military's political proxies, was plagued by complaints of cheating and the exclusion of Suu Kyi, who was released from seven straight years of house arrest shortly afterwards.
The NLD swept to a landslide election victory in 1990, when Suu Kyi was in detention, but the junta never recognised the result.Facts about Myanmar | Prisoner turned politician| Suu Kyi poised to win