Half the home pack inspectors won't be ready for the deadline

There were supposed to be 2,000 domestic energy assessors available to inspect properties put up for sale after June 1.

They will produce information packs that cost an average of £500, and include an energy performance certificate and key facts about a property such as local searches.

But Yvette Cooper has told MPs that only 1,100 of the inspectors had been accredited or were having their accreditation processed.

And as accreditation takes up to four weeks, the actual number available could be even fewer.

The housing minister said: "According to the latest estimates, 2,000 energy assessors will be needed at the beginning of June, rising to 2,500 by the end of the month."

A last- ditch Tory attempt to derail the legislation in the Commons has failed, as Labour MPs voted to pass the order implementing the packs.

Campaigners will try to challenge the order in the Lords. They are pinning their hopes on a judicial review launched by the Royal Institution of Chartered Surveyors.

It is claimed that the packs could trigger a crash in the housing market as sellers rush to sell their homes before the deadline.

Tory housing spokesman Michael Gove told MPs: "Yvette Cooper's admission that there simply aren't the number of people trained and accredited is deeply worrying for the housing market. It underlines how shambolic the Government's handling has been."

And he told MPs: "Ministers have botched this process from beginning to end."

Buyers already faced a "double whammy" of soaring stamp duty and a steep rise in mortgage payments as interest rates continue to climb, he added.

Mr Gove condemned the Government for ignoring warnings from the RICS, the Law Society and the Council of Mortgage Lenders.

But Miss Cooper said the plans were "sensible and practical".

She acknowledged opposition from some representative bodies, but said the RICS judicial review was completely groundless and focused against the energy certificates, not the whole pack.

"We do think that these are the right measures to introduce this summer," she added.

Gordon Brown has come under pressure to dump the packs and show that he has listened to campaigners.

But he missed the debate and did not vote to back the scheme.

Miss Cooper, who is tipped for a Cabinet promotion under Mr Brown, said the home packs were needed to cut carbon emissions from homes, which are responsible for about a quarter of the UK's entire output.