Some of America's largest corporations contributed to a charity that the US government claims deceived donors by funneling money to Osama bin Laden's al Qaeda network and other militant groups, according to court documents.

Microsoft Corp, Compaq and financial giant UBS made the donations over a number of years to match gifts that their employees made to Benevolence International Foundation before its director was indicted last year.

The disclosures were made in a filing by federal prosecutors in preparation for the upcoming trial of the charity's Syrian-born head, Enaam Aranout.

Prosecutors have alleged that the charity exploited the Islamic principle of giving, called zakat, victimising the donors who did not know where at least some of their money was really going.

Arnaout has denied any wrongdoing.

Prosecutors allege that Arnaout directed his charity to commingle millions of dollars of donations to hide the true purposes of the money. The charity's suburban Chicago headquarters was raided and its assets frozen in late 2001 as part of the US-led campaign to choke off funding for militant groups after the Sept 11, 2001 attacks on New York and Washington.

Microsoft, the world's largest software maker, confirmed that it had given about $20,000 in matching contributions.

"Upon learning of this organisation's suspicious activity in December 2001, we immediately suspended donations," said a Microsoft spokeswoman.

A spokesman for Hewlett-Packard, which now owns Compaq, confirmed the donations.

"Between March 1999 and October 2001, Compaq provided about $2,400 to the Benevolence International Foundation as part of its employee matching gift program," a spokesman said.

"Based on the charter of the foundation and the foundation's 501-C3 nonprofit status from the US government, Compaq determined that this organisation was humanitarian in nature.

Once the 501-C3 status was revoked in 2002, the organisation was no longer eligible for matching funds under the Compaq employee matching gift program."

Compaq, Microsoft and UBS are the only companies mentioned in the filing as having matched employee gifts. The papers made available on Thursday do not specify which segment or subsidiary of UBS might have been involved.