At least 13 people, including two policemen and two lawyers, were killed and 50 others injured on Tuesday in twin suicide bomb attacks in Bangladesh by suspected Islamic militants, witnesses and media reports said.

The bombs went off between 9 am and 9:30 am in the nearby Gazipur and southeastern Chittagong distrcts. No one has claimed responsibility for the attacks so far.

A man strapped with bombs around his body entered the lawyer's room of Gazipur court and set off the devices, witnesses said, adding that among the dead were two lawyers and the attacker, whose body was found wrapped in wire.

The injured, many of them with critical wounds, were rushed to local hospitals and also ferried to capital Dhaka.

Private NTV reported that at least 10 people were killed and 40 others injured in the suicide attack in Gazipur, suspected to be carried out by the banned Jamatul Mujaheedin Bangladesh.

In the other incident in southeastern Chittagong port city, a suicide attacker set off the device as police checked those arriving at the local court, killing three people, including two policemen, witnesses said.

The third was believe to be the suspected Islamic militant.

Police comment on the incidents was not yet available.

Angry Bangladeshi lawyers in different districts across the country started a boycott of courts to protest the bomb attacks.

Lawyers in Chittagong, Gazipur, Sylhet and other districts staged protest marches in court complexes.

The JMB, which seeks to establish strict Islamic rule in the Muslim-majority country, carried out previous attacks on courts.

The outfit first carried out attacks on August 17 in court and government office premises in 63 of Bangladesh's 64 districts, while a second attack was staged in October.

Two weeks ago, two assistant judges were killed in the southern town of Jhalakathi by a suspected suicide attacker also allegedly linked to the banned group.

Letters said to be sent by the JMB have continued to threaten judges and government officials across Bangladesh, including Supreme Court judges.

Security has been beefed up in courts and senior judges have been provided with police gunmen.

Meanwhile, police have arrested two people for their alleged role in sending bomb threats to several Western missions in Dhaka, including that of the US and Britain.

Police said a massive operation was carried out on Monday night to find out those behind the threat and the two were arrested from Dhaka.