The military government in Myanmar has threatened to take "effective action" against activists who have held protests across the country over the last three weeks.
Military rulers issued a statement accusing the National League for Democracy (NLD), headed by Aung San Suu Kyi, of trying to instigate nationwide unrest.
The move could lead to the NLD, the winner of elections in 1990 which the military nullified, being declared illegal.
The announcement said: "The NLD took advantage of the increase of fuel prices by the state and tried to exploit the situation to mount a political attack.
"They agitated through various means to instigate riots and unrest among the people.
"The NLD conspired to create this situation to derail the national political process."
Party denial The government also blamed the NLD for inciting Buddhist monks in the central town of Pakokku to destroy the homes and shops of pro-government militia leaders.
The monks also held about 20 government officials hostage for several hours last week, in the most dramatic standoff with the military government since protests broke out on August 19.
"Under these circumstances, the government will never tolerate such malicious acts and will take effective action against those committing such acts in accordance with the existing law," the statement said.
Nyan Win, an NLD spokesman denied that the party had done anything illegal.
"I don't think they have enough reasons to take legal action against the NLD because our party does not commit these things," he said.
More arrests
The statement had reinforced expectations that 13 detained activists who have been accused of "terrorism" - most of them leaders of the 88 Generation Student Group who spent long years in jail after the uprising - would be jailed again.
They were arrested in midnight raids shortly after they had organised a protest against a doubling of fuel prices.
The government had again defended the price hike in the statement on Sunday, saying it was necessary because current world oil prices had made fuel subsidies unaffordable.
Amnesty International has estimated that more than 150 people have been arrested over the protests.