Dhaka:  Two key leaders of an Islamist group blamed for a string of bombings across the country last year have been captured by Bangladesh security forces, an official said on Wednesday.

Khaled Safiullah and Mohammad Salahuddin were the last two members of the seven-member command council of the outlawed Jamaat-ul-Mujahideen group on the run since a crackdown began last year.

Safiullah was arrested along with his wife, three daughters and a younger brother from a house at Demra, on the outskirts of the capital Dhaka, early on Wednesday, the official said.

The other fugitive, Salahuddin, was picked up from a hideout at Kattali near the port city of Chittagong on Tuesday.

"With the capture of the two leaders, we have now arrested all seven members of the Jamaat-ul-Mujahideen Bangladesh's top decision making body, the Majlish-e-Shura, or ruling council," the Rapid Action Battalion commander said.

The elite battalion is at the forefront of the country's battle against Islamic militants and conducted a series of raids in the past weeks in their hunt for Salauddin and Saifullah.

Hasan said the two were leading the remnants of the group and were preparing for an attack on key government targets.

The Jamaat, along with another radical Islamist group, Jagrata Muslim Janata Bangladesh, has been fighting for introduction of harsh sharia laws in Bangladesh, a mainly Muslim democracy.

Jamaat-ul-Mujahideen Bangladesh's leader, Shaikh Abdur Rahman, was detained last month after a siege in the northeastern city of Sylhet.

The second in command, Siddiqul Islam, alias Bangla Bhai (Bangla brother), was caught after a gunbattle a week later.

Nearly 1,000 Jamaat-ul-Mujahideen Bangladesh members have been arrested, with 22 given death sentences.

At least 30 people were killed and more than 150 wounded in countrywide bomb attacks between August and December last year, blamed on the two groups.

The government has vowed to preserve Bangladesh's secular character and root out the extremists.