His decision to make an official comment to MSPs on Thursday follows accusations from opposition parties that he was deliberately "ducking the issue".

The BBC's Scotland Correspondent Andrew Cassell: "The media company says they made no promises"

Mike Russell, of the Scottish National Party, and the Conservatives' David McLetchie joined forces on Wednesday to condemn Mr Dewar's apparent silence on the matter.

Their attacks came as the Scottish Parliament's standards committee announced it would postpone beginning an inquiry into allegations surrounding public relations company Beattie Media and the Scottish Executive.

Donald Dewar: Under fire

Mr McLetchie said: "It seems to me that Mr Dewar is ducking the issue, he has dived for cover and he has tried to transfer responsibility to the standards committee. In that way he has failed to give the leadership we expect of him."

Mr Russell said Mr Dewar had been quick to address the media on the issue but not MSPs.

However presiding officer, Sir David Steel, had implied during a brief debate in the chamber on Wednesday that parliamentary procedures were such that Mr Dewar - who had signalled the need for an inquiry in the light of The Observer newspaper's allegations - could not make a statement.

Mike Rumbles: Committee convener

The parliament's standards committee agreed to adjourn and meet again on Tuesday - in private session.

That decision brought a further outcry from opposition members who said the debate should be in the open.

However, committee convener, Mike Rumbles, defended the decision and stated that because individual MSPs had been named, convention dictated that discussions took place behind closed doors.

Mr Rumbles said: "At the very first meeting of the committee it was decided that the most appropriate way to proceed is that if an MSP is named then we take the discussions in private session. We have to be seen to be fair to all those involved."

On Wednesday, The Observer handed over tapes and transcripts of an alleged meeting between an undercover journalist and two representatives from Beattie Media - including Scottish Secretary John Reid's son Kevin - to the standards committee 10 minutes before they were to meet.

Amid apparent confusion in the committee room, Mr Rumbles said that given the late access to transcripts it was best to adjourn the meeting.

The Observer says it was right to carry out the undercover investigations but people could judge for themselves by accessing the full transcript on its Internet site.

Jack McConnell: Named in story

Earlier on Wednesday, Finance Minister Jack McConnell, who was named in The Observer article, denied any wrongdoing.

And the company at the centre of the row, Beattie Media, issued a further statement on Wednesday.

It said it has received a full transcript of the allegations and is studying it carefully.

The statement added: "We want to re-emphasis that our executives declared during the meeting and later in writing that they would not and could not promise access to ministers."

The political row has been confined so far to procedural arguments as opposed to examining the substantive allegations.