A new campaign by the UK Border Agency has led to removal of more than 2,000 illegal migrants who were living in London.
Last May the Agency launched Operation Mayapple to crack down on students and other migrants staying in the UK longer than permitted.
Roughly two thirds were persuaded to leave voluntarily, with one third being removed by force.
Tactics used are varied.
The e-Borders system enables the UKBA to check which people have left the country and this information, along with other intelligence, is then used to contact those who breach the terms of their visas.
More than 400 London 'overstayers' were persuaded to leave the country after being contacted to inform them that they have no right to remain and must make arrangements to leave.
A further 800 left of their own accord and 58 overstayers left the capital under the Assisted Voluntary Return scheme, which is operated by Refugee Action.
More than 700 overstayers had to be forcibly removed following raids on businesses and residential premises in London, having refused to leave voluntarily.
Immigration Minister Damian Green met with the local immigration team for Bexley, Greenwich, Lambeth and Southwark ahead of a series of raids on Walworth Road and Atlantic Road in South London, during which three immigration offenders were detained.
He said: “We are working to ensure we identify anybody who has overstayed their visa and encourage them to leave the country voluntarily. Those tempted to overstay should be aware of the serious consequences. If you choose not to go you will be arrested, detained and removed.”
Anyone who fails to leave before their visa expires faces a ban on re-entry to the UK.
Of the 2,000 London cases, roughly a third were from India. Significant numbers of illegal migrants from Pakistan, Nigeria, China, Bangladesh and Brazil have also returned home as a result of the campaign.