Birmingham MP John Hemming is heading for a row with his party leaders over the future of Britain's post offices.

The Liberal Democrat MP for Yardley is to rebel against plans to privatise the Royal Mail at the party conference in Blackpool next week, just four months after being elected.

The controversial policy is one of a number of Lib Dem proposals which would see the party shed its Left-wing image.

Others include scrapping the commitment to raise the top rate of income tax to 50 per cent.

Party leaders are to present a motion to delegates calling for the complete separation of the Royal Mail and the post office network.

The Royal Mail could then be sold with the money ploughed into post offices to keep branches open.

The proposal will be presented by Norman Lamb, Liberal Democrat Trade and Industry spokesman, and if it wins the backing of delegates, it will become party policy.

He will argue that many of the shares could be given to Royal Mail staff and others could be sold to ordinary customers at post offices.

The rest would be floated on the stock market or sold to the highest bidder.

But Mr Hemming, who campaigned against the closure of post offices in Birmingham, is opposing the scheme.

A source close to the MP said: "It may be what the leadership wants but he's not prepared to back it, and he's planning to kick up a storm at the conference."

A Lib Dem source said: "We know it will be a controversial policy and a difficult debate because some people will simply see it as privatisation, although it is not. The aim is to keep post offices open rather than let it continue to decline.

"I'm not familiar with John Hemming's precise concerns, but if he's been arguing with people it doesn't come as any surprise."

More than 1,400 urban post offices were recently closed as part of a "reinvention" programme, which managers at Post Office Ltd said was necessary because of falling customer numbers.

The Lib Dems have been seen in recent years as being to the Left of Labour and many on the front bench are keen to return to traditional "liberal" values such as a commitment to the free market.

While the party has enjoyed electoral success attacking Tony Blair from the Left, this strategy could become more difficult if Gordon Brown takes over the Labour Party, as he is already seen as being more Left-wing than Tony Blair.