Aung San Suu Kyi's party says she has won a seat in Burma's parliament in today's landmark byelections, setting the stage for the pro-democracy icon to hold public office for the first time.

The victory, if confirmed, would mark a major milestone in the Southeast Asian country, where the military has ruled almost exclusively for a half-century and where the government is now seeking legitimacy and a lifting of Western sanctions.

The victory claim was displayed on a digital signboard above the opposition National League for Democracy's headquarters in Burma's main city, Rangoon.

Earlier, the party said in unofficial figures that Suu Kyi was ahead with 65 per cent of the vote in 82 of her constituency's 129 polling stations.

U.S. Secretary of State Hillary Rodham Clinton congratulated Myanmar for holding the poll. Speaking at a news conference in Istanbul, Turkey, she said Washington was committed to supporting the nation's reform effort.

Helped by a relative, an elderly woman casts her ballot at a polling station in Rangoon. The historic byelections are seen as an important vote of confidence for the country as it implements political reforms. (Mikhail Galustov/AFP/Getty)

"Even the most repressive regimes can reform, and even the most closed societies can open," she said.

Sunday's byelections, to fill a few dozen vacant seats in the country's legislature, followed months of surprising reforms by a nominally civilian government that does not relish ceding ground to Suu Kyi. But the leaders of Burma, also known as Myanmar, are making a push to appear more democratic in order to emerge from decades of international isolation that have crippled the economy.

Suu Kyi's party and its opposition allies will have almost no sway even if they win all the seats they are contesting, because the 664-seat parliament will remain dominated by the military and the military-backed ruling party. But when she takes office, it will symbolize a giant leap toward national reconciliation after nearly a quarter-century in which she spent most of her time under house arrest.

The 66-year-old Nobel Peace Prize laureate was vying to represent the constituency of Wah Thin Kha, one of dozens of dirt-poor villages south of Rangoon. She is running against the ruling party's Soe Win, a former army doctor.

'Psycho-social' victory for Burmese voters

Burmese democracy activist Maung Zarni, who is also a research fellow with the London School of Economics, cautions that Suu Kyi's victory would only be symbolic. He said even if her party won all of its seats, it would only represent eight per cent of the total seats in parliament.

"Politics is a numbers game. She is not likely to have much leverage, politically speaking, with the military junta," Zarni told CBC News on Sunday from a secret location in a neighbouring country. "At the end of the day, who calls the shot is the military."

Zarni said, for him, the biggest triumph was to see Burmese coming out to the polls to vote for Suu Kyi's party, calling it a "psycho-social" victory for his people who have remained cowed under an oppressive military regime.

Meanwhile, Suu Kyi's National League for Democracy party alleged Sunday that "rampant irregularities" had taken place on voting day.

Party spokesman Nyan Win said that by midday alone, the party had filed more than 50 complaints to the Election Commission. He said most alleged violations concerned waxed ballot papers that made it difficult to mark votes. There were also ballot cards that lacked the Election Commission's seal, which would render them invalid.

Push for reform

Last year, Burma's long-entrenched military junta handed power to a civilian government dominated by retired officers that skeptics decried as a proxy for continued military rule. But the new rulers — who came to power in a 2010 vote that critics say was neither free nor fair — have surprised the world with a wave of reform.

The government of President Thein Sein, himself a retired lieutenant-general, has freed political prisoners, signed truces with rebel groups and opened a direct dialogue with Suu Kyi, who wields enough moral authority to greatly influence the Burma policy of the United States and other powers.

Her decision to endorse Thein Sein's reforms so far and run in the election was a great gamble. Once in parliament, she can seek to influence policy and challenge the government from within. But she also risks legitimizing a regime she has fought against for decades while gaining little true legislative power.

Sunday's poll marks the first foray into electoral politics by Suu Kyi's National League for Democracy party since winning a landslide election victory in 1990. The military annulled those results and kept Suu Kyi in detention for much of the next two decades. The party boycotted the 2010 vote, but in January the government amended key electoral laws, paving the way for a run in this weekend's ballot.