Then, to stop anyone finding out, aides hid her role by virtually lying to Congress, the panel claims. The committee calls their testimony "unbeleivable", "highly implausible" and in one case,almost "contemptuous" of Capitol Hill.

It is an unprecedented attack on a First Lady. Mr Foster was found shot dead in a park in July 1993, but President Clinton is not mentioned as being involved in any conspiracy that night.

However, the committee cites "the Clintons and their associates" as part of "a larger and more troubling pattern" of "seeking to hinder and control" investigations of Whitewater. This dates back to "Arkansas in the 1980s" and continued in Washington.

"At every important turn, crucial documents 'disappeared' or were withheld from scrutiny whenever questions were raised". A report to be issued tonight , which has been extensively leaked, concludes that Mrs Clinton was so worried about sensitive documents relating to the land scandal falling into the hands of police investigating Mr Foster's alleged suicide that she "dispatched her trusted lieutenants to contain any embarrassment or damage".

In "misguided actions", the papers were "spirited" from Mr Foster's office at the executive mansion to the private quarters of Mrs Clinton.

At the time, Mrs Clinton was visiting her mother in Little Rock, Arkansas. The panel's evidence is based on telephone records revealing that a string of calls were made to her closest friend, Susan Thomases, a New York lawyer, and Maggie Williams, her chief-of-staff at the White House.

The committee says that the truth about what happened was in the evidence of a Secret Service agent who said he saw Ms Williams carrying a box of papers out of the office late that night.

Mr Foster had been involved in assisting the Clintons in responding to the Whitewater scandal, in addition to the furore over Mrs Clinton's role in the firing of staff in the White House travel office. Suspicion has surrounded the sudden discovery by an aide of the First Lady's billing records for her legal work for a firm involved in Whitewater.

Mr Starr will be asked to consider bringing charges of perjury against several witnesses

While the Whitewater report is partisan because it was prepared by the majority of the panel who are Republicans, the assessment, if acted on by Kenneth Starr, the Whitewater prosecutor, could be terribly damaging to the Clintons and their election campaign.

Mr Starr will be asked to consider bringing charges of perjury against several witnesses. If trials begin, Mrs Clinton may have to give evidence.

Polls show that Americans are becoming increasingly concerned that the truth is being concealed by the White House. In addition, a new survey cuts Mr Clinton's 20-point lead over Republican Robert Dole to six, a dramatic turnaround in the former senator's fortunes.

Fierce damage control was being mounted yesterday at the White House with Jane Sherburne, a lawyer, wondering how Republicans could say Mrs Clinton sought to hinder the Foster investigation without asking her about it.

"They come up with a conclusion like that having never dared to put the question to her? It's mind-boggling." Democrats on the committee said the Republicans were "politically grandstanding" by "targeting several witnesses with unsupportable suggestions of perjury in an attempt to grab media attention".

In an amazing response, a White House statement tried to laugh off the report. It suggested that the 200 hours that the panel devoted to examining witnesses could have been better spent in more important activities, such as watching Gone with the Wind 200 times or running 50 marathons.

There were a telling number of "I have no recollection" answers by supporters of Mrs Clinton questioned by the relentless Sen D'Amato

There were a telling number of "I have no recollection" answers by supporters of Mrs Clinton questioned by the relentless Sen D'Amato. Ms Williams and Mrs Thomases appeared to be deliberately vague about what was said in the telephone conversations with Mrs Clinton, classing them as simply exchanges of grief after the death of a friend.

The report homed in on what it called the "first suicide of a senior US official in almost 30 years", saying the circumstances of Mr Foster's death still remain "the subject of much speculation and even suspicion".

In assessing the Clintons as schemers who for years prior to the shooting had done their best to control the Whitewater affair, the panel cited the 1988 shredding by Mrs Clinton of some of her legal records, which the White House has explained was a routine effort to cut down on paperwork.

"By ordering their destruction, Mrs Clinton eliminated pertinent records and also exposed her firm to potential liability with respect to her representation." This was possibly a breach of ethics, or maybe even "a violation of law, if done with the knowledge that the documents are material to ongoing litigation".

The committee found it "especially troubling" that Webster Hubbell, her former law partner, now in prison for embezzlement, secretly removed Whitewater files from their firm when he left Arkansas after the 1992 election to become Assistant Attorney General in the Clinton administration.

Then, when police entered the Foster inquiry, "a concerted effort" was made by senior Clinton officials to block "a thorough investigation of a unique and disturbing event".

Richard Ben-Veniste, the chief Democratic lawyer to the committee, said that the presidential campaign had "undermined the objectivity" of the inquiry. He said that the conclusions were "clearly intended for political impact".