US investigators have raided dozens of jewellery stores across America suspected of laundering money for Osama bin Laden's al-Qaeda network, US officials have said.

About 75 jewellery kiosks, mainly owned by Pakistanis, were reportedly targeted by FBI and immigration officials over the past two weeks.

They took everything, my paperwork, bills, my computer, my cheques

Tariq Hussain, jewellery store owner

The stores came under suspicion after an employee was detained after spending hours photographing the World Trade Center days before it was destroyed.

More than a dozen people arrested in the raids are being held in custody on immigration charges, the Washington Post newspaper quoted officials as saying.

Anti-terrorism investigators are examining computer discs, documents and other material seized in the operation, the paper said.

Chain store targeted

Most of the raids involved the Intrigue Jewelers chain of stores, which are licensed from a Florida company called Gold Concept.

The US wants to stop funding for terrorist groups

The firm's chief officer, Arif Rajan, has been questioned by the FBI.

"He [Mr Rajan] sat down [with investigators] for several hours and answered all their questions," said Mr Rajan's lawyer, Phillip Calandrino.

"The general impression he got was that, by the end of the day, they were satisfied there was no wrongdoing," he said.

Investigators are continuing to question a Pakistani man who worked for Intrigue Jewelers after he spent hours photographing the Twin Towers before the 11 September attacks.

Muslim anger

The largest raids took place in jewellery stores in Pennsylvania, Florida, California, Alabama, Georgia and North Carolina at the end of last month.

These people are being confronted - and in some cases terrorised - based on no evidence

Ibrahim Hooper, Council on American-Islamic Relations

There were also operations in Pittsburgh, Atlanta, Texas, New York and Massachusetts.

The owner of Intrigue Jewelers in Pittsburgh, Tariq Hussain, said FBI agents questioned him for several hours and wanted to know about any links he had with bin Laden of al-Qaeda.

"They took everything, my paperwork, bills, my computer, my cheques," he said.

Civil liberty and Muslim groups have reacted angrily to the raids.

"These people are being confronted - and in some cases terrorised - based on no evidence," said Ibrahim Hooper, from the Council on American-Islamic Relations.

"Even when the FBI says there is evidence, it is never anything anyone else is allowed to see," he said.