Former prime minister John Major has backed Kenneth Clarke to become the next Conservative leader.

He told BBC Radio 4's Today programme that Clarke is "the most experienced candidate" and the man most able to attract the "non-aligned voters in the centre of politics".

"Kenneth Clarke is the best option for ensuring we win elections," he said.

Major attacked Iain Duncan Smith's record of voting against the last Conservative administration on European issues, saying he voted with Labour to defeat his government.

"Iain was one of a number of colleagues who voted night after night with the Labour Party in the Labour lobby with the purpose of defeating the Conservative government. Now that happened for a very long time. I understand he did that out of conviction. But I think that puts him in a very difficult position in one respect in particular.

"Since he voted consistently against the government he was elected to support, I think if, as leader, he asked the people to support him in a policy that they were uneasy about, I think he would be in a very difficult position in doing that credibly," he said.

Urging the Tories to urging to look beyond Europe, Major said," I am sick and tired of seeing the people I come from in the constituencies let down time and time and time again by people in parliament".

"We can only unite and defeat [Labour] if we reach out to the centre ground of politics. We cannot do it from the right wing. That is the fundamental point. The Conservative Party cannot pick up enough votes to win an election if it retreats to the right and doesn't reach out to those voters who are in the centre of politics," he said.

Major also rounded on Margaret Thatcher, accusing his predecessor of frustrating his attempts as prime minister to deal with the negative consequences of her legacy.

"Margaret wasn't very helpful during the 1990 to 1997 period, particularly the 1992 to 97 period. I think she forgot some of the difficulties she left behind with the recession, with rising unemployment, with very high interest rates, and was not very helpful as we took the difficult measures in order to get it down," he said.