Top Tory Andy Coulson cited for Tommy Sheridan perjury hearing

• Andy Coulson (left) with George Osborne. Pic PA

Andy Coulson, the Downing Street director of communications, has been directly linked to hacking into the phone messages of public figures while he was editor of the News of the World.

Now the under-fire adviser has received a letter from Mr Sheridan's legal team asking him to a pre-trial hearing that will determine whether he is called to give evidence at the trial of the former Scottish Socialist Party leader this autumn.

The letter from Mr Sheridan's solicitor Aamer Anwar, sent by recorded delivery and received at Downing Street yesterday, centres around Mr Coulson's time as editor of the News of the World, against whom the former MSP won a successful defamation action in 2006.

A Downing Street special adviser confirmed to The Scotsman that the letter "had been received", but said Mr Coulson would not be responding to the request at this stage.

However, if Mr Coulson refuses to appear at the trial of Mr Sheridan and his wife Gail, the spin doctor could be forced to attend under Scottish law.

Mr Sheridan won 200,000 in damages after the Sunday newspaper printed allegations about his private life.

He was later arrested and charged with perjury over statements he made during the defamation case. Mrs Sheridan is also accused of making false statements when she was a witness in the 2006 case.

The news came as the Prime Minister faced calls from within his own party to sack Mr Coulson.

A former reporter on the newspaper, Sean Hoare, yesterday alleged that Mr Coulson "actively encouraged" him to hack into phone messages and said that the spin doctor's denial of the claim was a "lie".

It is understood that Mr Sheridan's legal team want Mr Coulson to give evidence over his role in the News of the World's investigation into the former MSP. Mr Sheridan and his legal team refused to comment on the witness request last night.

Labour MPs stepped up the row yesterday, with former deputy prime minister Lord Prescott threatening legal action to find out whether reporters working under Mr Coulson hacked into his phone messages.

A senior Tory source told The Scotsman that the row was now "damaging" David Cameron and that the Prime Minister should sack his top press aide before it turned into a full-blown scandal.

The source said: "Coulson has been riding out this storm, but there's no sign of it abating and now it's starting to do damage to David Cameron and the party.

"It's time Coulson went before this gets even more serious. After all spin doctors are ten a penny.

"It was bad enough that this row was going on when we were in opposition. but to have it resurface now is just awful. David Cameron has to move on this and get rid of Coulson before this gets any worse."

The phone tapping allegations resurfaced after the New York Times claimed that Mr Coulson had openly discussed the use of unlawful phone-tapping when he edited the News of the World and "actively encouraged" Mr Hoare to illegally intercept voice messages.

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News of the World executives confirmed that a reporter had been suspended in connection with the phone-hacking scandal.

The paper's royal editor Clive Goodman was jailed for conspiracy to access messages in 2007.

Former home secretary Alan Johnson has now said a police-led probe may be needed to get to the bottom of the phone-tapping claims, which it is alleged included members of the Royal family.

Mr Johnson said he was considering asking Her Majesty's Inspectorate of Constabulary to review the Met Police's handling of the case. He went on to say that he would ask to see Home Office files relating to what he said were "extremely serious" allegations, under the convention allowing former ministers access to the information.

Dunfermline and West Fife Labour MP Thomas Docherty claimed that Mr Coulson's role in the affair smacked of "duplicity" and called on the Prime Minister to sack the former tabloid editor.

He said: "It would be too easy for Mr Coulson to resign, so the Prime Minister must sack him.

"There appears to be real political duplicity here and if these allegations are at all true David Cameron cannot allow Mr Coulson to simply resign.

"It's also hugely worrying to think that we could now have civil servants involved in defending Mr Coulson. I don't see how Mr Coulson can continue in his role working for the Prime Minister."

Meanwhile, Lord Prescott has said he would seek a judicial review if the police did not say whether claims his phone had been tapped were true.

He said he expected to hear from the police next week and, if he did not, he would take further action.

Aberdeen North Labour MP Frank Doran also questioned whether Mr Coulson should be allowed to continue as head of the Tory leader's media operation.

He said: "We have someone who's influential at the head of government, who's involved in the process of an investigation about illegal activity.

"It's clearly a serious offences we're talking about and has already resulted in the imprisonment of a journalist.

"It's difficult to see how someone who may have been aware of this should be allowed to have influence at the highest level of government."

Meanwhile, the Metropolitan Police said it would approach the New York Times to clarify aspects of its allegations over phone tapping.

A spokeswoman for 10 Downing Street said that Mr Coulson "totally and utterly" denied that he had instructed any of his reporters at the News of the World to get involved in phone hacking.

The News of the World released a statement denying that the use of phone tapping was "widespread" at the newspaper.

The statement said: "We reject absolutely any suggestion there was a widespread culture of wrong-doing at the News of the World."