NEW YORK, March 9: The Human Rights Watch on Wednesday asked the Pakistan government to immediately charge or release Zain Afzal and Kashan Afzal, US citizens of Pakistani origin who were abducted from their home in Karachi in August last year and have since "disappeared".

It also called on the US government to clarify its involvement in the case and whether the two were being held at its behest in Pakistan or elsewhere. FBI agents in Chicago have contacted relatives of the brothers, while witnesses allege that Americans were present and in radio contact with the abductors.

The New York-based rights group expressed concern about the possible role of the US government in this case. Nida Afzal, the Chicago-based sister of the two men, informed the Human Rights Watch that she had been telephoned by an FBI agent in late October.

She alleges that the agent "categorically stated" that "they (Zain Afzal and Kashan Afzal) are in our custody". Later that day, two FBI agents had come to see Nida Afzal at her home. The agents questioned her about her brothers' links to Afghanistan.

Witnesses told the Human Rights Watch that Zain and Kashan were abducted between midnight and 2am on August 13, 2004, in a raid that involved at least 30 armed Pakistani intelligence agents.

The agents broke through the concrete exterior wall and then broke into the house. Neighbours came out of their homes to see what was happening, but were ordered to go back inside.

The intelligence agents, in plainclothes, held the Afzal family at gunpoint for an hour, threatening to kill them while they searched the house. They specifically demanded to see the US passports and all other identity papers held by the brothers.

Once the papers were located, they handcuffed and hooded the brothers, and then left with them in a convoy of jeeps and vans typically used by Pakistan's intelligence agencies and police. Before they left, they locked the ailing mother of the two abductees in a bedroom.