Aung San Suu Kyi's opposition party on Saturday rejected the Myanmar junta's claim that more than 92 per cent of voters approved a military-backed constitution in the first round of a referendum last week.
"This result is completely incorrect," said Nyan Win, spokesman for the opposition National League for Democracy (NLD).
"They forced the people to vote Yes -- and did not allow ballots to be cast in secret," he told AFP.
Myanmar held the referendum across most of the country on May 10, even though huge swathes of land were still underwater from a cyclone that has left 133,000 people dead or missing.
The junta, which says the new constitution will pave the way to democratic elections in two years, announced on Thursday that 92.4 per cent of voters had approved the charter, with a 99 per cent turnout.
Nyan Win also said that the government should not have announced the results until the second round of voting May 24, when the regime plans to hold the balloting in areas devastated by the cyclone.
"This referendum result is not in accordance with the law. They should only announce the results after everyone finishes voting," he said.
The NLD has denounced the regime for holding the referendum while 2.5 million people still need food, shelter and medicine.
The party says the constitution will enshrine the power of the generals, who have ruled the country for nearly half a century.
The last time there was a national ballot, in 1990, Aung San Suu Kyi won in a landslide. She was never allowed to rule, and instead has been under house arrest for much of the time since.
Among its provisions, the constitution would make it illegal for her to ever hold office.