Coalition planning reforms which will be voted on tonight are a “recipe for community disharmony”, a Conservative MP leading a rebellion against the changes warned today.
Zac Goldsmith said easing rules on home extensions was an "odd" policy which undermined democracy.
Ministers announced last year that they intended a three-year relaxation of the depth of allowed single-storey extensions from 4m (13ft 1.5in) to 8m (26ft 3in) for detached houses and from 3m (9ft 10in) to 6m (19ft 8in) for all other houses.
Mr Goldsmith told the BBC Radio 4 Today programme: "It will guarantee disputes between neighbours, I don't think anyone doubts that. It will be very unpopular and there is no evidence, as far as I can see, that it is going to solve any problems at all.
"It seems like very bad, clumsy politics."
The plans have come in for widespread criticism on all sides of the House of Lords, and peers last month backed proposals which would give local authorities the option of rejecting the new rules in their area.
Local authorities, including Tory and Lib Dem town halls, yesterday urged MPs to back the "common-sense" amendment when it goes before MPs today, warning that the current plans risked "opening the floodgates" to thousands of unsightly house extensions.
Tory MP Heather Wheeler, however, insisted that the Government's plans would create jobs.
She told Today: "We are desperately short of family-sized houses. This is an opportunity to kick-start local economies."
Shadow communities and local government secretary Hilary Benn said: "This likely rebellion over planning laws shows the Government is so weak and divided that it can't even agree on how to build conservatories.
"This ill-conceived scheme to allow unregulated and potentially unsightly development without scrutiny is anti-localist and will sow discord between neighbours.
"If they really wanted to give an immediate lift to the construction sector they would take Labour's advice and cut the rate of VAT on home improvements and repairs, creating 100,000 jobs and helping both homeowners and builders."