LONDON, July 30 (UPI) -- The office of Prime Minister David Cameron Monday defended an ad campaign that encourages illegal immigrants to leave Britain.

The posters, which tell immigrants to "go home or face arrest," have appeared in a pilot effort in London neighborhoods where many immigrants live, The Independent reported. While a spokesman for Cameron defended the ads, they appear to have caused a rift in his Conservative Party's alliance with the Liberal Democrats, The Independent reported.


Business Secretary Vince Cable called the campaign "stupid and offensive." Matthew Oakeshott, a Liberal Democrat who sits in the House of Lords as Baron Oakeshott of Seagrove Bay, has also attacked the ads.

"This is a totally inappropriate use of public money for party political propaganda," he said.

A spokesman for the prime minister said the ad campaign "is working." The Home Office was unable to say how the government knows the ads are working, the Independent said.