DHAKA, BANGLADESH, NOV. 11 -- The government of Bangladesh placed the country's two main opposition leaders under house arrest today as sporadic demonstrations continued against President Hussein Mohammed Ershad.

Abdul Matin, the minister of home affairs, said the violence had spread from Dhaka, the capital, to other areas of the country. Protesters halted trains in Mymensingh and set fire to buildings in Chittagong. In Dhaka, the U.S. Information Agency's cultural center was gutted by fire.

But there were no additional reports of police gunfire. At least three people were killed yesterday in Dhaka when policemen opened fire on demonstrators.

Early today, police officers broke into a suite in a downtown Dhaka hotel and arrested Begum Khaleda Zia, leader of the Bangladesh National Party. Zia refused to leave the hotel, and when the officers finally persuaded her to do so, she leaned out of an open window, her sari flapping in the breeze, and urged her followers in the street to carry on.

Hasina Wajed of the Awami League, the other important opposition group, was prevented from leaving her home to meet the press.

Meanwhile, the opposition appeared to have achieved only partial success in calling for merchants and businessmen to shut down and for the operators of private transportation companies to suspend service. About one shop in five was open for business, and hundreds of pedicabs moved through the streets.