DHAKA, 4 January 2006 — Police tightened security yesterday at a natural gas field in northern Bangladesh after a bomb threat by a banned extremist group blamed for a string of deadly blasts.

“We have received a complaint from Shahijibazar gas field that their deputy general manager got a letter from Jamatul Mujahedeen warning that it would blow up the gas field,” said Mili Biswas, superintendent of Habiganj district, 300 kilometers northeast of the capital.

“We have taken the threat seriously. Security has been stepped up immediately and police are investigating,” she said of the state-owned gas field.

Police believe Jamatul Mujahedeen is responsible for a series of blasts across Bangladesh since August that have killed 28 people, including four suicide bombers. Leaflets left at blast sites bearing the name of the group called for the imposition of Shariah law.

The judiciary has been a prime target of the bombers, with four lawyers and two judges among the dead.

The blasts have shaken Bangladesh, which cherishes its reputation as a moderate Muslim nation and secular state.

The country, which has two religious parties in its four-party coalition government, has mobilized thousands of police, army and paramilitary troops to search for members of the group led by Afghan war veteran Shaikh Abdur Rahman.

Meanwhile, Bangladesh Army and border guards yesterday seized a huge cache of weapons from a hide-out in a remote southeastern district bordering Myanmar, an official statement said.

Authorities also caught three suspects described as foreigners during the operation early yesterday at Naikkhongchari in Bandarban district, 248 kilometers southeast of the capital, Dhaka, according to the statement of the Bangladesh Rifles, the country’s border security force.

The weapons and ammunition include five M-16 rifles, one AK-47 rifle, one light machine gun, seven 12-bore rifles, two 303 rifles and 7,000 rounds of bullets.

The identities of the arrested were not disclosed immediately, but it was believed that they belonged to a Myanmar separatist group, local television station ATN Bangla said.

The border guards have recently stepped up patrols in the area based on intelligence indicating the region is being used as a route for arms smuggling through neighboring Myanmar and India.

In September, the border guards recovered two huge cache of weapons and ammunition from the same area.

The district is one of three areas where Bangladeshi tribal rebels waged a 25-year insurgency seeking greater autonomy before signing a 1997 peace deal with the government.