Deputy Prime Minister Nick Clegg has unveiled new plans for a harder line on immigration.
Mr Clegg called for a bail-like system of "security bonds" to tackle visa abuse - refundable cash guarantees to be paid by immigrants from so-called "high-risk" countries.
In his first speech on immigration as Deputy Prime Minister, the Lib Dem leader said visa "overstayers" are one of the biggest challenges the immigration system and the UK Border Agency faces.
Mr Clegg has asked the Home Office to run a pilot of the bonds, which echoes an Australian system applied to family visas.
It is understood the cost of the bonds would vary, but they are likely to cost at least £1,000.
The Deputy Prime Minister said he will be seeking views on the proposal, including from the Home Affairs Select Committee.
But the committee's chairman, Labour MP Keith Vaz, has rubbished the plans.
Mr Vaz said, "Those who support these schemes have little understanding as to how our entry clearance operation works".
Shadow Immigration Minister Chris Bryant has also warned that the proposal is potentially unfair.
Mr Bryant said it could discriminate against people who genuinely want to visit for a short period but are too poor to pay the deposit, while "unscrupulous people" who can afford it may be willing to "fork out their one or two thousand pounds" in order to circumvent the system.