CHARLES KENNEDY is expected to be subjected to a Commons investigation over his failure to declare more than £30,000 of free flights from his party’s most generous donor, who is wanted by police in America.

The Liberal Democrat leader took seven flights in a twin- engine jet paid for by the businessman Michael Brown. Mr Brown’s £2.4 million donation to the party, the biggest in its history, is being studied by the Electoral Commission because it may have breached the ban on foreign donations.

None of the flights is recorded in Mr Kennedy’s declaration to the Commons authorities. By contrast Michael Howard, the Tory leader, and Alex Salmond, leader of the Scottish National Party. have declared flights paid for by supporters.

Chris Grayling, the Shadow Leader of the Commons, wrote to Mr Kennedy last night, putting him on notice that the Conservatives will refer the case to the Parliamentary Commissioner for Standards today.

“I am particularly surprised to see from your entry in the Register of Members’ interests that you have not declared the gift made by Mr Brown to you of the use of an aircraft over a number of days earlier this year,” he wrote.

“Although some of this use appears to have been during the general election campaign, when you were not an MP, you appear to be the only party leader who has not declared the donation of plane or helicopter use in the most recently published register. In doing so, you appear to have left yourself open to an investigation by the Commissioner.”

Commons rules state that MPs must register any donation of £1,000 or more that is linked either to candidacy at an election or being an MP.

The Liberal Democrats waited until May 6, the day after the general election, to register six flights at £5,000 each with the Electoral Commission. They failed to declare at all an earlier flight from London City airport on March 4 for the Liberal Democrats’ spring conference at Harrogate.

Mr Kennedy’s spokeswoman said: “Mr Brown was going up to Harrogate and offered Mr Kennedy a lift in his aeroplane. Charles was going up anyway and decided to take the lift. His car was driven up by someone else. Because there was no cost benefit, it was considered unnecessary to declare it.”

Mr Brown said yesterday that the Lib Dems had suggested he go to the conference. “I was going up there anyway and I did offer Charles a lift.”

The two men flew back from Leeds-Bradford airport with Mr Kennedy’s wife, Sarah. “She was pregnant at that time so it was a quick way to get down,” Mr Brown said. He paid a rate of €800 (£550) per hour for that flight.

Mr Brown is wanted in Florida after breaching probation in a cheque fraud case. He has said that he did not realise he was a wanted man and has instructed American lawyers to resolve the issue.

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