People leaving the UK may soon face immigration checks as part of the government's on-going battle over asylum seekers.

Home Office minister Beverley Hughes has told MPs that she is considering bringing back a Customs procedure ditched by the Conservative government 10 years ago which checked details of people leaving UK air and sea ports.

Her department is trying trace the thousands of asylum seekers who disappear each year after arriving in the UK.

The immigration minister admitted officials were finding it "extremely difficult" to establish how many failed asylum seekers were still in the UK.

"Some work is being done on what it would cost to reinstate an embarkation check," she told the home affairs committee.

"There are technical issues around that too. We don't currently have an embarkation check - that was abandoned some 10 years ago - and it's something we're prepared to examine."

Over recent weeks the government has come under fire from all sides of the asylum debate.

Concluding its evidence sessions on removals, the committee quizzed Hughes on whether the government's policies towards removals are realistic, humane, effective and unconstrained.

Last year the Home Office was forced to scrap its target of removing 30,000 failed applicants for asylum back to their country of origin each year after consistently failing to achieve it.

Home secretary David Blunkett described the target as "over-ambitious".

"We should not set targets which are not achievable," he said.

Meanwhile, critics on the left are angry that the government has threatened to pull out of international treaties on asylum if they cannot "stem the tide" of immigration into the country.