Sources in the law enforcement agencies said he is suspected to have a connection with the August 17 blasts.

Masud, who was on the way to London, was arrested at around 10:00am by the Immigration Police under high-level government instruction.

However, the government is playing hush-hush on the arrest. It is not clear now which law enforcement agency has taken him into custody.

When contacted, the immigration officials at ZIA expressed their ignorance about Masud's arrest. The officer in charge of the Airport Police Station also gave a similar response to The Daily Star.

But intelligence sources point out that after the immigration police arrested him, Masud was taken to an unknown location. One source pointed out that he was taken to the Directorate General of Forces Intelligence (DGFI).

According to multiple sources, the police headquarters had informed the immigration authorities in advance not to allow Masud to fly abroad, if he makes any such attempt.

Hailing from Kishoreganj's Tarail area, around 60-year-old Masud joined the Islamic Foundation prior to 1980 as a translator dealing with Arabic to Bangla translation. He was gradually promoted to the level of Director of Publications in the early nineties.

He was finally assigned as the Director of the Imam Training Academy in the mid-nineties. In November 2001, he is said to have resigned from the post.

According to his former colleagues, Masud has been a mysterious character but he is reputed as an Islamic scholar who owns a NGO, a hospital, an Islamic School and a madrasa.

"We heard that he has wide international connections. He received funds from the Middle East, and the UK to run these enterprises," said one of his former colleagues.

"After his 2001 resignation, we heard that he had widely travelled abroad for quite some time," he added.

Masud's Madani Hospital is located in the capital's Green Road area, and NGO Isla-hul-Muslemin Parishad and Ikra Bangladesh (a religious school having countrywide network) in Rampura. Masud also teaches at another madrasa in Khilgaon Taltola. He is also involved in Jamia Shariah Madrasa at Malibagh.

Another former colleague of Masud said he had heard that Masud had obtained huge foreign funds through his NGO.

During his directorship of the Imam Academy, he headed the national Imam association (Jatiya Imam Samity).

A former colleague pointed out last night, "During his service, we were not aware of his political affiliation. He has in-depth knowledge of Islam. Very few people can teach Bukhari Hadith Sharif, which he did. He had many Islamic degreesincluding one from India's Deoband Madrasa."

The Deoband based Islamic education is orthodox in its teaching.

Talking to The Daily Star, Masud's brother Arifuddin Maruf last night said he (Masud) was going to London on a personal visit. "We do not know why he was arrested and where he is now. There is no question of his link to any militant organisations and the August 17 bomb blasts."

"Masud was never involved in politics," he added.