Myanmar democracy icon Aung San Suu Kyi has been elected to the country's parliament in landmark by-elections, according to her National League for Democracy (NLD).

The country's opposition party claimed a historic victory on Sunday for Suu Kyi in her bid for a seat in parliament, with NLD announcing that the Nobel laureate had won a parliamentary seat for the first time.

Suu Kyi won an estimated 99 per cent of the votes in Kawhmu constituency, according to NLD official Soe Win, based on the party's own tally. There was no independent confirmation and official results were expected within a week.

Thousands of people clapped and cheered outside NLD headquarters in Yangon after the party announced the iconic leader's victory.

Some people wept with joy at the news outside the party's headquarters in Yangon.

The charismatic leader did not address the crowd but issued a statement asking supporters to respect the other parties.

"It is natural that the NLD members and their supporters are joyous at this point," Suu Kyi said.

"However, it is necessary to avoid manners and actions that will make the other parties and members upset. It is very important that NLD members take special care that the success of the people is a dignified one."

This marks a stunning turnaround for Suu Kyi, who was a political prisoner, jailed by the military-led government for most of the past 22 years.

The NLD also said it has won all the 44 seats it contested in Sunday's elections.

Suu Kyi's win is "hugely symbolic," said Al Jazeera's Wayne Hay, reporting from Yangon.

"And while she will have little power, the mere fact that she is there means there will be a lot more international attention on parliament itself and the decisions that it makes."

Our correspondet said that the success of these elections might mean bigger gains for the opposition in the upcoming 2015 general elections.

"Still, there is this nagging problem that a quarter of all seats in parliament must go to the military - that is written into the constitution," said Hay, adding the Suu Kyi has been very open about wanting to change that provision.

Democratic reforms

Sunday's vote is seen as a key test of the government's commitment to recent democratic reforms.

More than six million people were eligible to vote on Sunday, with a total of 160 candidates from 17 parties, including six new to the political stage, contesting for 45 parliamentary seats.

The number of seats at stake is not enough to threaten the military-backed ruling party's overwhelming majority, secured in full elections in 2010.

Suu Kyi's apparent victory had been widely expected, despite complaints by the NLD over alleged voting irregularities and campaign intimidation.

She said she did not regret standing for parliament because the polls had boosted people's interest in politics after decades of outright military rule ended last year.

The government for the first time invited teams of foreign observers from the Association of Southeast Asian Nations, European Union and the US, and journalists to witness the elections.

Since taking office a year ago, President Thein Sein has carried out reforms including releasing hundreds of political prisoners, easing media restrictions and welcoming the opposition back into mainstream politics.

The NLD won a landslide election victory in 1990 but the ruling military never allowed it to take office. The party also boycotted the 2010 polls that swept the army's political proxies to power and were marred by complaints of cheating and intimidation.

Suu Kyi described the vote as "a step towards step one in democracy", despite complaining on Friday that the polls were not "genuinely free and fair".