Speculation was mounting last night that Clare Short may be preparing to quit Labour and join the Liberal Democrats.

The Birmingham Ladywood MP spent yesterday in her House of Commons office refusing to answer telephone calls and working on a speech setting out her future plans.

Furious Labour Party officials have still not been able to contact Ms Short three days after she reportedly announced her decision to stand down at the next General Election.

All attempts to clarify matters by the party's West Midlands regional office have been unsuccessful.

Under Labour's reselection rules, Ms Short has until tomorrow to tell officials whether she wishes to stand at the next General Election as the party's official candidate.

Reselection had been considered a foregone conclusion until the MP reportedly told a seminar at Kingston University, London, that she intended to stand down in order to campaign for a hung Parliament.

As reported in The Birmingham Post yesterday, according to a website Ms Short told academics that she wanted the next Government to do a deal with the Liberal Democrats to introduce proportional representation.

The former member of Tony Blair's Cabinet was said to have described the Labour Government as a failure and a historic wasted opportunity.

Westminster insiders believe the natural course for Ms Short would be to join the Liberal Democrats.