Only days earlier US president Barack Obama had stood alongside Ms Suu Kyi in Yangon and said a law banning her from becoming president after elections in November next year "doesn't make much sense."

Myanmar's powerful parliament speaker Shwe Mann said the current military-drafted constitution cannot be changed before the elections.

The constitution bars anyone with a foreign spouse or children from becoming president, a clause believed to have been specifically written to thwart Ms Suu Kyi, whose late husband and two sons are British.

Ms Suu Kyi, 69, and her National League for Democracy (NLD) are expected to make huge gains at the elections which are seen as a test of the credibility of reforms that began in 2011.

However, reforms hailed by Western nations such as the United States and Australia have stalled for 12 months as the country's military protected its wealth and power, analysts say.

Ms Suu Kyi has made clear she wants to become president and last week told Mr Obama on the sidelines of the APEC meeting in Myanmar the constitution was "unfair, unjust and undemocratic".

NLD officials declined to immediately comment on Mr Shwe Mann's announcement, saying it was still unclear whether the government was categorically ruling out Ms Suu Kyi contesting the presidency.

Mr Shwe Mann announced that a nationwide referendum on constitutional changes would be held in May next year.

But he told reporters it would not be possible to implement them before the elections, adding they would come into force only after the new parliament is seated.

The current constitution is widely seen as undemocratic because it gives 25 per cent of parliament's seats and other special political powers to the military.

Mr Obama last week sounded a word of caution about the country's reform process, saying it was "by no means complete or irreversible."