Richard Butler is asked if intelligence operations were carried out with his approval

Unscom was set up after Iraq's defeat in the Gulf War of 1991 to track down and destroy Iraqi weapons of mass destruction.

Using interviews with former weapons inspectors, and with Unscom chief Richard Butler, investigative journalist Tom Mangold alleges that:

• The infiltration began in 1996 when weapons inspectors grew impatient with Iraqi efforts to "lie, cheat and deceive".

• American and British inspectors began to take over specific Unscom operations, thereby compromising the UN's independence.

• In one case, codenamed "Operation Teacup", a team of Unscom personnel - who were in fact working for US and British intelligence - thwarted an Iraqi attempt to obtain banned material in Romania.

• US intelligence agents succeeded in smuggling into Baghdad a large and sophisticated listening device known as "Stephanie". The device was kept in the office safe of American weapons inspector, Scott Ritter.

Scott Ritter: "Unscom wasn't in control of anything"

According to Mr Ritter - who resigned from Unscom last year - the US took over the whole "Stephanie" operation.

And, he says, the most sensitive information from "Stephanie" went to US intelligence, not to Unscom.

Nick Childs reports: "The allegations have fuelled controversy surrounding the organisation."

In Operation Desert Fox last December, when the US and Britain launched sustained air strikes on Iraq, they used the "Stephanie" material to help them choose their targets, the programme says.

According to Scott Ritter, "the US killed Unscom" - a charge flatly denied by Richard Butler.