A YouTube video, apparently filmed on a mobile phone, shows Mrs Clark embroiled in a row with staff in the bar of a city centre hotel.

During the 73-second clip, she furiously accuses a hotel employee of victimising and humiliating her.

When the former Labour MP was contacted by The Evening Telegraph yesterday, she declined to comment on the video but said she would be seeking legal advice.

She said: "I will be contacting my lawyers.

"I don't want to say anything about it, but obviously I will be taking legal action."

Mrs Clark, who served as Peterborough's MP between 1997 and 2005, is shown in the film sitting with a friend at a table in the bar area of the Great Northern Hotel.

The footage begins part way through a heated exchange between Mrs Clark and an unseen female employee.

Although it is not clear from the clip what the dispute is about, the poster of the video claims it was sparked after Mrs Clark was refused service by staff.

Loudly protesting she has been wronged by the hotel worker, she says: "Why was I treated like this?"

Mrs Clark then appears to become distressed and says: "I was just sitting here. I did nothing wrong. What did I do wrong?"

Bosses at the hotel, opposite the city's railway station, claimed they were unaware of the video yesterday, and declined to say whether or not any action was being taken against staff or if Mrs Clark was still welcome there.

Manager Paulette Walters said: "I haven't seen (the film) and I don't really want to comment."

Mrs Clark enjoyed an eight-year spell as Peterborough's MP and was one of the original "Blair Babes" when she won the constituency during Labour's sweeping general election victory in 1997.

She was re-elected in 2001 before losing her seat, four years later, to current city MP, Conservative Stewart Jackson.

Law of defamation applies online

Material posted on the Internet is subject to exactly the same legal rules as material printed in a newspaper or magazine, or broadcast on television or radio.

That means online statements or footage which have the potential to cause damage to a person's reputation are covered by the laws of defamation, as they are anywhere else.

To protect themselves against legal action for libel, website hosts have a responsibility to ensure their sites do not contain any defamatory material.

Problems arise for websites such as YouTube, however, because of their sheer size.

With millions of people using the video-sharing site every day, and millions of clips from around the world available to view, it is extremely difficult to monitor it properly.

Any defamatory material which does find its way online could result in whoever posted it, as well as the host of the website, being prosecuted.