The new coalition government wants to cut the number of MPs
The government is pressing ahead with plans to redraw constituency boundaries across the UK and cut MP numbers.
Ministers are preparing a bill that will be presented to the Commons before the summer which could see the number of MPs cut from 650 to below 600.
Constituencies would also have similar number of voters under the plans, which Labour say will benefit the Tories.
Cabinet Office minister Mark Harper said the aim was for fairness and to "reduce the cost of politics".
Conservatives believe the varying sizes of constituencies means each Tory MP needs far more votes than a Labour MP to secure a seat in Westminster.
Constituencies like the Isle of Wight, for example, has 110,000 voters, while the Western Isles has only 22,000 voters.
The Lib Dems back plans to cut the number of MPs and "equalise" constituency sizes but Labour say the plans are designed to eliminate smaller inner-city seats which they hold.
The government will now instruct the Boundaries Commission to draw up a new constituency map of Britain, with fewer than 600 seats, each with an equal number of voters.
Mr Harper said: "We propose to do two things. To reduce the size of Parliament, to reduce the number of MPs, to reduce the cost of politics, which I think most members of the public would agree with.
"And we also have the proposal to have more equal-sized constituencies because it's fairer. So we're not introducing these proposals now in response to the general election result, they were in the Conservative manifesto beforehand."
The proposals are part of a range of political reforms proposed by the new coalition government.
These include establishing fixed-term, five-year parliaments and ensuring 55% of MPs are needed to back dissolution of Parliament.
Other measures include bringing in a referendum on voting reform, moves towards electing the House of Lords, and funding 200 all-postal primaries for parliamentary seats which have not changed hands in many years.