NEW YORK, Oct 31: Thousands of immigrants, mainly from Muslim countries, were rounded up by US authorities in 2004 in an operation meant to disrupt potential terrorist plots before and after that year’s presidential election, The New York Times revealed in a report on Friday.

The programme, conducted by the Department of Homeland Security, received little public attention at the time. But details about the targets of the probe have emerged from more than 10,000 pages of internal records obtained through a lawsuit by civil rights advocates. Parts of the documents were provided to NYT.

The documents show that more than 2,500 foreigners in the United States were sought as “priority leads” in the autumn of 2004 because of suspicions that they could present threats to national security in the months before the presidential election and the inauguration.

Some of those foreigners were detained and ultimately deported because they had overstayed their visas, but many were in the country legally, and the vast majority were not charged.

The internal reports show that immigration agents questioned the foreigners about what they thought of America, whether violence was preached at their mosques, and whether they had access to biological or chemical weapons.

A sampling of 300 cases turned over by federal officials showed that none of those interrogated were charged with national security offences. Fewer than one in five were charged, most of them with immigration violations.

The detention of more than 700 illegal immigrants as terrorism suspects generated a blistering report from the Justice Department on the “unduly harsh” treatment of the prisoners.

Follow-up efforts in 2002 and 2003 led to the questioning of thousands of Muslims and Middle Easterners as well as measures requiring that immigrants from some countries register their presence with federal authorities.