BBC Scotland Political Editor Brian Taylor reports

Committee convener Mike Rumbles said MSPs on the parliamentary watchdog were agreed that they should "move swiftly" to investigate the allegations in The Observer newspaper whether or not lobbyists had disproportionate influence over ministers.

The committee agreed a series of measures after meeting in open session to watch a film of discussions between employees of a lobbying company and a journalist posing as a potential client.

Mike Rumbles: Swift investigation

The committee agreed to appoint a special adviser to collect information relevant to the investigation.

Once that report has been received, the committee said it would then interview those individuals relevant to the inquiry.

These include Observer journalists involved in the investigation and Scottish Executive ministers Jack McConnell, Sam Galbraith, Jackie Baillie and Henry McLeish, who were named in discussions with Beattie Media staff.

Committee member James Douglas-Hamilton on the key issues for the inquiry

Kevin Reid, the son of Scottish Secretary Dr John Reid and Alex Barr, the two representatives of the lobbying arm of Beattie Media who were filmed, would also be required to attend.

Trade Minister Lord Macdonald of Tradeston would be asked to attend, although he could not be ordered to appear before the inquiry as he is a UK Government minister.

Scottish First Minster Donald Dewar has been asked to provide evidence and all witnesses summoned must do so on oath.

Publish report

Mr Rumbles said he hoped to complete the investigation quickly and publish a report in the first week of November.

He said: "The point of this investigation is that we want to act quickly, we want to act openly and we want to act effectively."

Mike Rumbles: "We are committed to openness and accountability"

After controversy over the committee's decision to meet in private last week when it first received film and transcript evidence from The Observer, Mr Rumbles said further meetings of the committee would be in open session.

He said: "I would like to go on record to remind everybody on this committee and all those who are watching this that if you look through the previous minutes ... you will see every member of this committee committed themselves to openness, accountability accessibility.

"Only in exceptional circumstances we reserve the right to meet in private. This investigation will be in public view."

Jack McConnell: To face inquiry

The inquiry was prompted following allegations in The Observer newspaper that the lobbyists were promising improper access to members of the Scottish Executive.

The newspaper filmed the two men allegedly telling the journalist that they had influence with ministers and in particular Mr McConnell, a former Beattie Media employee.

Speaking at the standards meeting, Mr Rumbles was clearly keen to dispel concerns about secrecy which arose last week.

On receipt of The Observer material, the committee decided that because individual MSPs were named in allegations, parliamentary convention dictated that, at least initially, its members should meet in closed sessions to discuss the terms of reference for their inquiry.

The action prompted criticism from opposition MSPs and court action by The Scotsman newspaper which, it said, was intended to establish the principle of openness in the parliament.

Meanwhile, the parliament's Deputy Presiding Officer Patricia Ferguson confirmed she had resigned from the committee.

She said that her previous role as a Scottish Officer for the Labour Party while Mr McConnell was Scottish general secretary created a conflict of interest.