Burma’s military-backed government assured visiting top EU officials on Monday that upcoming by-elections heralding the opposition’s return to mainstream politics will be democratic.

“We have taken the necessary measures so that the upcoming by-elections will be free, fair and credible,” lower house speaker Shwe Mann told EU development commissioner Andris Piebalgs, speaking through an interpreter.

Piebalgs, carrying an EU pledge to provide €150 million euros ($US200 million) in additional aid to Burma over the next two years, also held private talks with President Thein Sein and voiced optimism about the changes.

“It is sustainable, what is happening here, but let’s keep our eyes open,” Piebalgs said. “You feel that no one doubts the sincerity of the reforms even if they have some disagreement about what is happening now.”

The 1 April polls, which will see Nobel Peace Prize winner Aung San Suu Kyi stand for a seat in parliament for the first time, are viewed as a key test of the authorities’ commitment to budding reforms.

A 2010 election which swept the army’s political allies to power was marred by widespread complaints of cheating and intimidation.

The opposition cannot threaten the ruling party’s majority even if it takes all 48 available seats in the by-elections, but a Suu Kyi win would lend legitimacy to the fledgling parliament.

Her National League for Democracy (NLD) party won a landslide victory in an election in 1990, but the then-ruling junta never allowed the party to take power.

Suu Kyi was under house arrest at the time. She was released from her latest stint in detention a few days after the 2010 vote.

The upcoming polls are being held to fill places vacated by those who have since become government and deputy ministers.

Piebalgs, who was accompanied by German development minister Dirk Niebel, was set to meet Suu Kyi on Tuesday.

After nearly half a century of outright military rule, the regime has surprised observers with reforms including welcoming the opposition back into the official political arena and releasing hundreds of dissidents.

Shwe Mann, a former general who is a key figure in the new regime, acknowledged there were “still some remaining political prisoners”, but added “the remaining prisoners are those who have committed criminal activities”.

The European Union agreed in January to begin easing sanctions on Burma, lifting travel bans against the nation’s leaders and pledging further action if the reforms continue.

The 27-nation bloc will progressively re-examine its sanctions, which include an arms embargo, a ban on gems and an assets freeze on nearly 500 people and 900 entities.

“Once we’re confident that the elections are free, fair and democratic then I’m very hopeful that the sanctions will be lifted,” Niebel said after Monday’s talks.

The EU has provided 174 millions euros to the Southeast Asian nation since 1996 to help combat malaria and tuberculosis, improve conditions in rural areas and send more than six million children to school.