The closure of dozens of Sussex post offices will go ahead as planned after a last ditch attempt to save them was defeated in Parliament last night.

A Tory motion demanding Post Office bosses "suspend" the Government's programme to axe up to 2,500 branches across the UK - including about 50 in Sussex - was rejected by a majority of just 20 votes.

The motion was supported by Conservative MPs in the county and Norman Baker, Liberal Democrat MP Lewes, but opposed by Labour MPs, even though three of them - Brighton Pavilion's David Lepper, Hove's Celia Barlow and Hastings and Rye's Michael Foster - have campaigned against closures in their constituencies.

Tory Post Offices spokesman Charles Hendry, MP for Wealden, accused Labour MPs of a "betrayal of the most vulnerable people in their constituencies that will haunt them for the rest of their careers".

He said: "Constituents will simply not be able to understand how MPs told them they were on their side but when they had the chance to vote against closures they failed to do so."

But Mr Lepper said suspending the current round of closures would cause "even more uncertainty" for people.

He said: "I accept the national strategy on post offices, but that doesn't mean I have to accept closures in my constituency if I think there's a good case for keeping them open."

Hastings MP Michael Foster accused the Tories of "hypocrisy" for failing to commit to spending any more than the Government's agreed £1.7 billion subsidy for the network.

He said: "It's a fact that some post offices are unviable. To suggest there should be no closures at all, like the motion, is unrealistic. I will not be induced to support the Tories' gesturing until they are prepared to come up with the funds."

Earlier, a Tory MP from Sussex launched a withering attack on Post Office bosses in the Commons.

Tim Loughton, whose constituency of East Worthing and Shoreham is expected to lose half its 14 sub-post offices, said: "I have never dealt with a more duplicitous, bullying, self-serving, incompetent, arrogant and out of touch body than the Post Office has proved itself to be in this consultation."

Tory leader David Cameron said the Government seemed happy to "manage the decline" of the Post Office network.

Business secretary John Hutton called on Post Office bosses to give "serious consideration" to rescue packages put forward by councils to keep local branches open