WASHINGTON, May 17: Former Pakistan prime minister Benazir Bhutto has been summoned to appear before a US federal grand jury that is hearing evidence in the campaign fund-raising inquiry involving American politicians.

Bhutto, currently in the United States on a lecture tour, was served a subpoena earlier this week seeking to question her about efforts by Congressmen Dan Burton to pressure her lobbyist Mark Siegel to raise campaign contributions for him.

Seigel had claimed in a memo to the Bhutto government in July last year that he was ``shaken down'' by Congressman Burton for campaign contributions in return for representing Pakistani interests in the Hill. The memo was in reply to a message from a Bhutto aide chastising Siegel for not being helpful to Burton who is a ``friend of Pakistan.''

``I should tell you that I worked in Washington for 25 years and have never been shaken down by anyone before like Dan Burton's threats. No one has ever dared to threaten me into contributing money, no one has ever followed through on such threats by contacting my clients,'' Siegel wrote in the memo, which was leaked to the US media recently when Burton began investigating Democratic fund-raising practices.

Siegel, a prominent Democratic lobbyist in Washington, has already testified before the grand jury. Although his contract as Pakistan lobbyist has not been renewed by the Nawaz Sharief government, Siegel is still close to Benazir and was at hand in New York last week to meet her on the first leg of her two-week US tour. Bhutto is currently in Seattle.

Dan Burton is heading a House investigation of Democratic fund-raising practices, but he himself is in deep trouble over the same issue and is the focus of a similar inquiry by the Clinton administration's justice department task force. Latest reports say he is also a recipient of munificence from the fleeing Zairian dictator Mobutu Sese Seko.