Campaigning has begun in Myanmar, two months ahead of its first openly-contested general election in 25 years.

Aung San Suu Kyi's National League for Democracy is expected to win the most seats, while losses are predicted for the ruling military-backed party.

Suu Kyi is standing for parliament but is constitutionally barred from becoming president.

Over 90 parties will stand in the first national polls since a nominally civilian government took power in 2011.

In a video message released on her party's Facebook page, Nobel Peace Prize-winner Aung San Suu Kyi called for a free and fair election.

"For the first time in decades our people will have a real chance of bringing about real change," she said. "This is a chance that we cannot afford to let slip."

Highlighting concern the military might not respect a result that went against them, she added: "A smooth and tranquil transition is almost more important than a free and fair election."

Military veto

The constitution of Myanmar, also known as Burma, grants the military at least 25% of parliamentary seats, so the NLD and any allies will need to win at least two-thirds of the remaining seats in order to choose the next president.

Even if the NLD does win a parliamentary majority, the military is still guaranteed a veto over any constitutional change and its commander-in-chief will still control key ministerial appointments.

The last time the party took part in a national election was in 1990, and they won by a landslide. But the result was ignored by the military, which kept Ms Suu Kyi under house arrest for 15 years.

The NLD boycotted the next nationwide poll in 2010, which was won by the ruling Union Solidarity and Development Party (USDP) despite widespread accusations of vote-rigging.

But a week after it was held Ms Suu Kyi was released and her party stood in 2012 by-elections, winning 43 of the 44 seats it contested, including her own.

Pre-election politics

The campaign begins less then a month after a major presidential contender and opponent of President Thein Sein, powerful parliamentary speaker Shwe Mann, was removed as USDP party leader.

His dismissal was seen as a move by Thein Sein to tighten his political grip ahead of the vote.