WASHINGTON, Nov 28: More than a third of those rounded up after the Sept 11 attacks and still in custody are people of Pakistani origin, according to official figures released here on Tuesday.

Attorney-General John Ashcroft, under pressure to release details of those being kept in federal custody, said 641 people were in detention of whom over 200 came to the United States from Pakistan. These are among 548 held on immigration charges.

Pakistan embassy sources had earlier said they had information about 70 of those arrested who were Pakistani nationals, that is, those who held valid Pakistani passports. The others must be those who had either applied for or acquired US citizenship or did not have valid documents and who had not informed the embassy of their detention.

The issue was taken up with President George Bush by a 15-member delegation of Pakistani Americans that was invited to the White House for talks on Tuesday afternoon. The talks, on the overall picture of US-Pakistan relations, were mainly with National Security Council officials, but President Bush had also joined in for about half an hour.

Pakistani community organizations, unlike Arab American associations, have generally not been very vocal about the issue of detained Pakistanis, saying that they have often not been informed of those who have been arrested or who have been victims of hate crimes and racial profiling.

Mr Ashcroft said at his news conference that of the total number of 641 people still in custody, 548 faced immigration charges; the rest were detained on what he called federal criminal charges. The names of those on immigrations charges were not released, only the numbers and nationalities were detailed. The 104 charged with federal criminal violations were, however, named.

According to Justice Department figures, of the 548 persons held on immigration violations, 208 came to this country from Pakistan. The vast majority of the others are from the Middle East, including Egypt (74), Jordan, Yemen, Iran, Algeria, Morocco, Syria, Afghanistan and Saudi Arabia. Twenty Indians are also being held.

Being held at various lockup facilities nationwide —- including New York, where some are being questioned by the Justice Department’s terrorism task force —- those in custody on immigration charges have reportedly been accused of a vast range of suspected crimes, from misuse of a passport to fraud.

News reports on Wednesday said some were arrested after being found in possession of box cutters similar to those used by the terrorists who crashed three jetliners into the World Trade Centre and the Pentagon.

More than 1,182 persons have been arrested since the attacks, although more than 400 have since been cleared and released. Forty-nine others face federal charges and are being sought or are free on bail. Mr Ashcroft alleged that some of those in custody were memebrs of Al Qaeda.

Under vastly increased powers authorized by the attorney-general, 5,000 people, mostly of Arab descent, have been sent letters “inviting” them to cooperate with authorities in answering questions relating to terrorist networks. The federal government has also assumed authority to increase electronic surveillance of suspects.

A leading member of the Senate judiciary committee, Senator Russell Feingold, a staunch opponent of the new anti-terrorism laws, said in a statement after Mr Ashcroft’s news confeence that he was deeply troubled by the attorney-geneal’s refusal to provide a full accounting of everyone who had been detained and the reasons for denttion.