Several home-made bombs exploded at Dhaka University as Awami League and BNP students fought over control of the campus.
 
Police said no one was hurt but tension was high. Around 40 students were injured in fighting between rival groups in the Jagannath Hall campus of university, witnesses said.
 
Police also dispersed a protest by Awami League supporters outside Dhaka's presidential palace.
 
Witnesses said about 5,000 protesters gathered around the palace but riot police prevented them from moving closer.
 
Election battle
 
A 14-party alliance led by Hasina and BNP dissidents has called for a siege to force the country's interim government to fire key election commission officials, including acting chief Mahfuzur Rahman.
 
Rahman took over this week after his boss, Aziz, stepped down temporarily.
 
The Awami League said on Saturday they would not take part in an election under Rahman.
 
"We want Mahfuzur Rahman and his cronies removed immediately to create a congenial atmosphere for people to exercise their franchise in an absolutely free and peaceful manner," said the Awami League general secretary, Abdul Jalil.
 
"Unless it is done, we will launch a bigger movement to force President Iajuddin to resign as chief adviser of the caretaker authority."
 
The opposition has accused Aziz of creating a list of fake voters to skew the outcome of January's presidential elections.