The number of Scottish MPs at Westminster will be cut to 59

MPs are expected to give final approval on Monday to the legislation, which will bring about a major reduction in the Westminster total.

The Commons will vote on an order giving final legal footing to new boundary changes.

The shake-up will reduce the number of parliamentary constituencies from 72 to 59.

The Commons vote will make legal the recommendations of the Boundary Commission for Scotland, which decided on the cutback after a long inquiry.

It means, as a consequence of devolution, larger constituencies similar to those in England and 13 fewer seats for potential Scottish MPs to fight over.

Westminster cull

The House of Lords is expected to give its backing to the legislation next week.

The result is that when voters go to the polls they will be electing 646 MPs rather than the current 659.

Scottish Secretary Alistair Darling has told MPs he intends to lay parliamentary orders as soon as possible to bring the changes in before the public goes to the polls.

English constituencies currently contain nearly 70,000 voters on average, far more than the Scottish average of 53,500.

The move is seen as a means of restoring parity following devolution, which supporters say made the need for extra Scottish MPs redundant.

Alistair Darling is driving through the plans in time for the next election

The Scotland Act, which paved the way for the establishment of the Scottish Parliament, contained an agreement to end the anomaly of Scotland's over-representation at Westminster.

The final recommendations in the fifth periodical review were released just over a year ago following a lengthy consultation exercise and a series of public inquiries.

A number of cabinet ministers face seeing their constituencies disappear in the redistribution, including Chancellor Gordon Brown, Health Secretary John Reid and even Mr Darling himself.

However, the ministers are expected to be given new constituencies when Labour draws up its list of parliamentary candidates for the next election.