YANGON  - Myanmar was making final preparations Saturday for polls seen as a test of the military-dominated regime's reforms, in which opposition leader Aung San Suu Kyi is standing for the first time.

Many polling stations in the 45 constituencies spread across the country were already set up for the Sunday vote, which the Nobel laureate is contesting despite criticising it as not "genuinely free and fair".

Suu Kyi was set to make her way later Saturday to her rural constituency of Kawhmu, about two hours drive from Yangon.

The participation of "The Lady", as she is known, and her National League for Democracy (NLD) party has fuelled an explosion in the number of T-shirt vendors in the main commercial city of Yangon, with an every-increasing variety of styles, all of which would have been taboo just a year ago.

"We must win," states the latest design, a red shirt with Suu Kyi's face printed in black.

A carnival atmosphere pervaded in Mingalar Taung Nyunt township, one of six constituencies up for grabs in Yangon, on the last day of campaigning Friday.

Large flatbed trucks crammed with people, from young children to the elderly, travelled through the streets blaring music, including the popular campaign song about Suu Kyi "Our mom is back".

There was obvious glee at being able to display political allegiance freely.

Many supporters, wearing red NLD bandanas and T-shirts, had plastered their faces with stickers of the party logo -- a red background with a yellow fighting peacock and a white star.

"We have done a lot of preparation for April 1. We have polling station representatives and people to provide information, because we want to know what's going on. The result will match people's desires.

The NLD must win," local NLD candidate Phyu Phyu Thin told AFP.

NLD supporters Saturday erected a giant LED screen outside the party headquarters in Yangon to broadcast the results as they come in.

In the city's Mayangone constituency, officials set out tables and labelled ballot boxes at a polling station in a high school.

"Authorities sent us a blueprint of how to prepare the polling station and we have laid it out exactly as they instructed," said school teacher Myint Ngwe, who was in charge of the preparations.

Suu Kyi on Friday renewed complaints of irregularities in the run up to the by-elections, including vandalism of party posters and "intimidation".

But the 66-year-old, who was under house arrest during elections in 1990 and 2010, 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 NLD won a landslide election victory in 1990 but the junta 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.

Experts believe the regime wants the pro-democracy leader to win a seat in parliament to burnish its reform credentials and encourage an end to Western sanctions.

The NLD is contesting 44 seats and estimates vary as to how many it could win.

Thiha Saw of local weekly news journal Open News said he expected the party to win a little over 50 percent of the available seats. But bookies have predicted 32 seats for the NLD from betting -- technically illegal in Myanmar -- on the results.

The number of seats at stake is not enough to threaten the military-backed ruling party's overwhelming majority in parliament but Suu Kyi described the vote as "a step towards step one in democracy".

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 government has for the first time invited teams of foreign observers and journalists to witness the elections.

A total of 160 candidates from 17 parties, including six new to the political stage, are contesting the polls.