DHAKA: Prison authorities in Bangladesh's southern city of Khulna on Sunday executed a senior Islamic extremist whose banned group has been linked to the murder of foreign hostages, police said.

Asadul Islam, 42, a leader of the outlawed Jamayetul Mujahideen Bangladesh (JMB), was hanged for his role in a 2005 blast that killed two judges.

Bangladesh has blamed the JMB for the July 1 attack on an upmarket Dhaka cafe in which 22 people, mostly foreign hostages, were killed.

"He was hanged to death at 10:30 pm (1630 GMT) in Khulna jail," Khulna Police Commissioner Nibhas Chandra Majhi told AFP, adding that there was heavy security around the jail to prevent any violence.

Islam, also known as Arif, was one of seven senior JMB officials, including founding leader Shaikh Abdur Rahman, sentenced to death for a bomb attack on a minibus that killed two lower court judges on November 14, 2005.

Six of the men, including Rahman, were executed in March 2007 by a military-backed caretaker government as part of a nationwide crackdown on Islamic extremists.

Arif was sentenced in absentia and was not detained until July 2007. He has been held in Khulna jail ever since. In August the Supreme Court dismissed his final appeal.

His execution comes as Bangladeshi security forces push a deadly new crackdown against Islamist extremists following the cafe attack that has shaken the image of Bangladesh as a moderate Muslim nation.

Since July, police have shot dead nearly 40 suspected extremists including JMB's new leader Tamim Chowdhury, a Canadian citizen of Bangladesh descent who allegedly masterminded the cafe carnage.

As part of the crackdown, Bangladesh's courts have also fast-tracked prosecution of Islamist extremists, scores of whom were already facing death sentences and languishing in the country's jails.

Majihi said hundreds of police and the elite Rapid Action Battalion have been deployed in Khulna, the country's third largest city, and key roads leading to the jails had been blocked to prevent any violence.

A prison official told AFP that Arif had refused to seek presidential clemency -- his last chance to stop the hanging -- which prompted the authorities to prepare for his execution.

Founded in the late 1990s by Islamists who fought in the Afghan wars alongside the Taliban, the JMB seeks to impose sharia law on Bangladesh, a Muslim majority but officially secular nation of 160 million people.

JMB first shot to prominence in Bangladesh when it conducted a coordinated bombing attack on August 17, 2005, with more than 400 small blasts in 63 of the country's 64 districts.

Many of those bombs targeted secular courts.