Conservative MPs have accused the Liberal Democrats of treachery after plans to redraw the UK electoral map were humiliatingly defeated.

The changes would have given the Tories some 20 extra safe seats at the next General Election. But the Conservatives were outvoted by parties including their LibDem Coalition colleagues. The vote was Nick Clegg's revenge for last year's dumping of his plans to reform the House of Lords.

Smaller parties including the SNP also voted against the changes, effectively killing Tory hopes of a last-minute victory.

Prime Minister David Cameron had previously pleaded with parties from Scotland, Wales and Northern Ireland to help him defy Mr Clegg.

But SNP MP Pete Wishart told MPs that even though the proposed changes would benefit his party they would give the Conservatives "no comfort".

The plans were defeated by a humiliating 334 to 292 votes, and it means any changes will now be put off until 2018.

Tory MPs condemned those who opposed the plans. There was fury for Mr Clegg, who had initially championed the policy on the grounds of fairness.

Conservative backbencher Penny Mordaunt said the LibDems had been motivated by "spite, pettiness and self-interest" and accused them of making "flirtatious glances" to Labour ahead of the next election.

"The Liberals have exchanged their legendary sandals for flip-flops in the hope that it will enable them to keep their options open," she said.

Others within her party warned their opponents would be punished by the electorate for wasting taxpayers' money.

The Conservatives say the plans, which would have cut the number of MPs from 650 to 600 and equalise the number of voters in each constituency, would save millions of pounds. But opponents disputed the figures and accused the Tories of a plan to spend more by increasing the number of peers.

The boundary changes were seen by many Tories as a key part of their plans for the 2015 General Election. The party is keenly aware that it failed to win outright in 2010. With LibDem votes ministers would have easily had enough votes to pass the changes. But Mr Clegg announced last year his party would oppose the plans in retaliation for what he said was backtracking over Lords reform.

The review had long proved controversial with Labour accusing the Coalition of "gerrymandering". Jack Straw yesterday repeated those claims, attacking Conservative ministers for "wholly partisan" plans.

As well as all 57 Liberal Democrat MPs, four Tories also rebelled against the plans.