Chandrika Kumaratunga made the moves while her political rival, Prime Minister Ranil Wickremesinghe, was in Washington to meet with President Bush. The president has said the prime minister was too soft in his peace talks with the rebels.
Troops were sent to the state television and radio stations and to a main power plant after the government announced that it fired the defense and interior ministers — in charge of the military and police, respectively — and the information minister.
"Several platoons have been deployed to prevent any unwanted incidents and to maintain law and order," military spokesman Col. Sumeda Perera told The Associated Press.
Soldiers were seen armed with T-56 rifles. However, no incidents were reported and the city was calm as people returned home from work. Troops on the streets are a common sight because of the civil war and terrorism.
Kumaratunga gave no reason for suspending the 225-seat Parliament for two weeks, but her opponents have a thin two-seat majority.
"The irresponsible and precipitous action of the president is aimed at plunging the country into chaos and anarchy," said Wickremesinghe, who remains prime minister. He and other Sri Lankan officials were holding an emergency meeting in Washington on Tuesday. Wickremesinghe was scheduled to meet Bush on Wednesday.
Kumaratunga has been severely critical of how the prime minister has handled peace efforts with the Tamil Tiger rebels, arguing that his government has given too many concessions without ensuring that the Tigers abandon their armed struggle for self-rule.
For example, she accused the prime minister of entertaining rebel demands for autonomy without insisting they disarm first.
Wickremesinghe said the president's "irresponsible and precipitous action" will not deter his administration's peace efforts.
"I therefore call upon all of the people, the armed forces, police and public service to remain calm and vigilant in the face of this deliberate attempt to endanger the peace process," the prime minister said in a statement.
Kumaratunga's office said in a statement that the move to sack the ministers was "taken after careful consideration in order to prevent further deterioration of the security situation in the country." It did not elaborate.
The United States and Britain have backed peace talks. Washington has branded the Tigers a terrorist organization.
"The recent political developments in Sri Lanka must not be allowed to jeopardize that process," Britain's Foreign Office said.
Defense Minister Tilak Marapone, Interior Minister John Amaratunga and Information Minister Imthiaz Bakeer Markar — who helped spearhead the fragile peace process — were removed from those posts Tuesday, government spokesman Giruka Perusinghe said. Three top aides to the ministers also were fired.
However, the three fired ministers still hold other Cabinet-level portfolios.
"All these ministries are now under the president and will continue to remain so," Janadasa Peiris, the president's media director, told AP.
Kumaratunga, who is from a different political party than Wickremesinghe, is commander of the armed forces and has wide authority under the constitution to dismiss the government and call new elections.
Defense Secretary Austin Fernando, contacted by telephone in London, said he had been informed of the president's move but declined to comment further.
Tamil Tiger rebels also declined to comment.
"We do not want to comment until we receive full details of what has happened," rebel spokesman Daya Master said.
On Friday, the rebels submitted a plan for an interim administration in the war-battered northeast. They want powers to collect taxes and control the administration of the northeast, where most of the island's 3.2 million minority Tamils live.
The rebels signed a cease-fire agreement with Wickremesinghe's government in February 2002, halting two decades of fighting that killed 65,000 people. The Tigers launched their war to seek an independent homeland for Hindu Tamils, arguing discrimination at the hands of the Buddhist Sinhalese majority.
The rebels dropped their demand for independence — saying they would settle for regional autonomy — during six rounds of peace talks. But the rebels walked out of those talks in April, saying the government had not done enough to resettle refugees and redevelop Tamil areas.
Expanded autonomy is a key rebel demand for returning to the peace talks.