Voters in Burma cast ballots Sunday in parliamentary elections seen as a crucial test of the country's democratic reform progress.

Candidates vied for 45 seats in the 664-seat parliament in the first by-elections since the new, nominally civilian government took office in March of last year.

Main opposition leader Aung San Suu Kyi, who heads the National League for Democracy, ran for the first time since 1990 when her party won a landslide victory in general elections. At the time, military leaders refused to relinquish power and kept her in some form of detention for most of the next 20 years.

The NLD alleged Sunday that some ballot papers had been covered in wax, which could be rubbed off later to change the votes. The opposition also complained of voter intimidation. Aung San Suu Kyi has said she does not expect Burma's election to be fair, but said it is still significant.

A 2010 general election, won by military-backed candidates was marred by widespread complaints of cheating and the exclusion of the NLD, which boycotted the election because the party's iconic leader and Nobel laureate was not permitted to run.

Aung San Suu Kyi was released from house arrest shortly after the November 2010 elections and got actively engaged in the political process. She is widely expected to win because of her popularity.

Whatever the outcome, the by-elections will not give the opposition enough parliamentary power to achieve its goal of revising the constitution, which secures overwhelming power for the military.

For the first time, the government has invited a small number of foreign observers and journalists to witness the elections.

The official results are expected in about a week.