Labour MPs have rejected proposals to give their new leader the right to choose his or her own shadow cabinet, giving potential for divisions in the party's front rank.

The Parliamentary Labour Party voted down reforms which would have ended the party's practice in opposition of selecting the shadow cabinet by a ballot of MPs.

Yesterday's vote - which also rejected alternatives under which the leader could have appointed half or one-third of the top team - will create a headache for whoever is elected Gordon Brown's successor on September 25.

An elected shadow cabinet is almost certain to mean the new leader having to find top jobs for MPs with whom they do not see eye-to-eye politically.

Some of the new leader's closest political allies may be also denied shadow cabinet posts if they are unable to persuade enough of their parliamentary colleagues to back them.

The system forced Tony Blair, in opposition, to have left-wingers such as Michael Meacher, Frank Dobson and Gavin Strang around his top table. It may hand a place in the new shadow cabinet to Diane Abbott if she fails in her bid for the leadership.

The leader will, however, have the power to decide which portfolio to hand to each member of the shadow cabinet.

Yesterday's vote also increases the minimum number of women among the 19 elected shadow cabinet places from four to six.

But MPs rejected alternative proposals for a 40 per cent or 50 per cent minimum.

The PLP also approved a change to its rulebook which will see the chief whip elected separately to serve a full Parliament.

This change strengthens the chief whip's position, and there is speculation at Westminster that the current holder of the post, Nick Brown, is aiming to retain it for the coming five years to create an independent power base for his close confidant Mr Brown.

In a further change to the rulebook, MPs voted yesterday to make the shadow cabinet elections two-yearly, rather than annual as they were when the party was last in opposition 13 years ago.

Nominations open at the start of the Labour conference on September 26 for the 19 elected members who will make up the shadow cabinet alongside ex-officio members like the party leader, deputy leader and chief whip.

The party's 257 MPs will vote for their 19 preferred candidates - of whom at least six must be women and six men - over a number of days and the result will be announced on October 7.

Yesterday's rulebook changes must be formally endorsed at a meeting of the PLP next week.