Tony Blair's business interests are in the spotlight
Tony Blair was cleared by a vetting panel before carrying out work for an oil giant and did not keep it secret, the former PM's office has said.
It emerged this week that Mr Blair had been paid for advising the UI Energy Corporation, a South Korean oil firm with interests in Iraq and the US.
The details were released by a panel which vets jobs taken by ministers.
Lib Dem frontbencher Norman Baker called for a probe to be launched into Mr Blair's business interests.
But the ex-prime minister's office insisted he had done nothing wrong.
Mr Blair's spokesman said: "Mr Blair gave a one-off piece of advice in respect of a project for UI Energy in August 2008.
"He sought, and received, approval from the Committee on Business Appointments before undertaking this project.
"UI Energy requested of the committee that they delay public announcement for reasons of market sensitivity, which the Committee agreed to do."
In addition to carrying out work for UI Energy, the Advisory Committee on Business Appointments also disclosed Mr Blair had been acting as a "governance adviser" to the Kuwaiti government since June 2008 in a deal reportedly worth £1m.
It said publication had been delayed at the request of the Kuwaitis.
The committee, chaired by former Conservative Cabinet minister Ian Lang, vets ministers and senior officials who take jobs within two years of leaving government.
The committee cleared both of Mr Blair's appointments
But Norman Baker said he believed Mr Blair could be in breach of the Ministerial Code of Conduct in relation to the extensive business interests he has taken on since leaving office in June 2007.
He said he had written three times to Prime Minister Gordon Brown asking him to investigate - as well as raising the issue on the floor of the Commons - but so far had not received a substantive reply.
"Mr Brown appears to be desperately trying to avoid giving an answer before the general election. He is playing for time," he said.
He said Mr Blair's business activities reflected badly on both Britain and the wider international community which now employed him as an international envoy on the Middle East.
"Mr Blair's pursuit of money appears too prominent and wholly compromises his position as a Middle East peace envoy. He is embarrassing the country and this government by the way he behaves," he said.
Douglas Carswell, a backbench Tory MP who campaigns for political reform, said Mr Blair's link to UI Energy Corporation "stinks".
He told the Daily Mail: "It seems that the former prime minister of the United Kingdom has been in the pay of a very big foreign oil corporation and we have been kept in the dark about it.
"Even now we do not know what he was paid or what the company got out of it. We need that information now.
"This is revolving door politics at its worst. It's not as if Mr Blair has even stepped back from politics, because he is still politically active in the Middle East.
"I'm afraid I have no confidence at all in the committee that vets these appointments. It's no good telling us these deals may be commercially sensitive - we are talking about the appointment of our former prime minister and the public interest, rather than any commercial interests, must come first."
Mr Blair is the envoy of the Quartet of Middle East peace negotiators among a number of other roles he has taken up since standing down.