Failed asylum seekers will be driven underground because of David Blunkett's latest plan to curb abuses in the system, according to an influential committee of MPs.

The home secretary wants unsuccessful applicants who refuse a government-funded flight home to lose their social security benefits.

However, the report from the Commons home affairs committee warns the government that for some families the measure would be an incentive to disappear, while "leaving their children in the care of local authorities at public expense".

Meanwhile government figures have revealed that the average asylum seeker's family costs the UK taxpayer £16,000 a year.