They are considered a new breed of Islamic fundamentalists. They study at top British and American schools yet abhor Western values, advocate a pan-Islamic state and favor the removal of Pakistan's pro-U.S. government.
Militancy and violence is not part of their agenda; they want to achieve their "lofty goals" through peaceful and non-violent struggle.
But analysts say such men, fired by the passion of an Islamic renaissance, stand on a thin line dividing political and violent struggle.
Hizb ut-Tahrir (Liberation Party), an international Islamic group with roots from England to Central Asia, is a recent addition to myriad radical organizations striving to enforce "true Islam" in Pakistan, a poor South Asian nation.
The group was outlawed in Pakistan in Nov. 2003, just three years after it started operations, but its members continue undeterred, distributing party literature and holding small meetings in efforts to expand their base.
Pakistan, an ally of the United States in the war on terror, banned several militant Islamic groups, but most re-emerged under new names. Hizb ut-Tahrir has refused to change its identity despite the closure of offices and the arrest of several members.
British and U.S. nationals of Pakistani origin comprise the backbone of this secretive group formed in Jerusalem in 1953.
It wants to establish a supra-Islamic state on the model of the caliphate as it existed in the early days of Islam.
The group came to Pakistan through second-generation Pakistanis living in the West, particularly Britain and the United States. They claim they had supporters in Pakistan for a long time but formal operations took longer to establish.
Many members abandoned what they call the luxuries of the West to come to Pakistan to live among fellow Muslims and work for the country's transformation into a puritanical Islamic society of their dreams.
"In terms of living standards, England is better. You don't confront problems such as water shortages, power failures there," a Hizb member, who works as an executive at a bank, told Reuters, requesting anonymity.
"But you cannot safeguard the Islamic way of life in a Western society. You become alienated," said the 32-year-old, who migrated from his birthplace, London, to Pakistan -- the country of his parents -- two years ago.
"We believe the change will come in the Muslim world from places like Pakistan, where an overwhelming number of people are Islamic-minded," he said in a clipped British accent.
MANY RETURN TO ROOTS
Scores of young men like him moved to Pakistan mainly from Britain and the United States to work for the Islamic cause.
With their trimmed beards and Western clothes, they stand in contrast to the turban and skull cap-wearing traditional followers of local Islamic parties. But their anti-West rhetoric is as radical as that of their more orthodox counterparts.
Intelligence officials say the shadowy network is taking root among educated Pakistanis and a few of its members are under surveillance. Group members include engineers, accountants, computer experts and doctors.
Several of its members speaking to Reuters in separate interviews, some on the condition of anonymity, said the number of their supporters was increasing.
"We advocate unity of Muslims," said Ismail Sheikh, a frail 34-year-old British national of Pakistani origin who was arrested for distributing pamphlets outside a Karachi mosque in July.
But an anti-terrorism court acquitted him on lack of evidence last month and he was back to organizational work the same day, saying the arrest only strengthened his resolve."
"They questioned me whether I had links to al Qaeda, or I visited Afghanistan," said Sheikh, a dentist from the University of Wales. He abandoned his medical career in London and moved to Karachi in 1999 to become one of the group's pioneer members.
The government sees Hizb ut-Tahrir as a threat.
"Its activities were found prejudicial to the national interest," said Abdul Rauf Chaudhry, an interior ministry spokesman. "Its members incite people against the government through their writings and leaflets."
But Naveed Butt, Hizb ut-Tahrir's spokesman, said to bring about a change one needed political, not militant action.
"We are being associated with militancy because we preach an alternative ideology," said Butt, an engineer from Chicago, where he was first introduced to the group in the mid-1980s.
"The best barometer of our success is that we were banned within three years of our activities here."
Ahmed Rashid, author of a book on the Afghan Taliban, said Hizb was a movement based in Europe.
"Young Muslims living in the West get exposure to their culture through religion.
"I don't think they have any real popular support. Given the enormous number of Islamic schools and parties, it is difficult for someone like Hizb, which is seen as an import from England, to come in the field and make room for itself."