Dozens of students and police have been injured in two days of rioting on university campuses in Bangladesh.

Correspondents say the unrest is the most serious challenge yet to the military-backed emergency government.

The violence took place in three universities in or near the capital, Dhaka, as well as in the southern city of Chittagong and Kushtia in the west.

Late on Tuesday, officials said troops would withdraw from Dhaka University, one of the students' main demands.

Protests are banned in Bangladesh under a state of emergency announced by the military-backed caretaker government which took power six months ago.

'Troublemakers'

Many of the demonstrators called for the country to return to democracy, which the government has promised to restore by the end of next year.

In the worst clashes at Dhaka University, students threw stones and lit fires across the campus. Police responded with batons and tear gas.

The students burnt an effigy of the army chief, Moeen U Ahmed, and tried to assault the vice chancellor, police said.

Dozens of vehicles were set on fire, including an army jeep.

The BBC's Waliur Rahman in Dhaka says that two other military governments in the past - that of Ziaur Rahman and Muhammad Ershad - were both brought down in protests that were started by students.

The army is reported to be keeping a low profile in the clashes, leaving the job of confronting the students to the police.

But the government has said that action will be taken against troublemakers, who it says will be removed from campuses if necessary.

Late on Tuesday the authorities offered to remove the contentious army camp in Dhaka. They also announced a judicial inquiry into the riots and said soldiers could face prosecution.

Troops are accused of triggering the violence at Dhaka University by picking a fight with students.

Students in Dhaka told the BBC that they wanted the army not only to leave the university but also to withdraw from politics.

There was widespread popular support for the interim government when it came to power in January, vowing to stamp out corruption before returning the country to democracy.

But discontent has been rising in recent months, most notably over with the rapidly rising cost of living.

PHOTO CAPTION

Student protester