Media playback is unsupported on your device Media caption Suresh Grover, civil rights activist: "Why did they contact me?'

David Cameron "agrees with the principle" of sending text messages suggesting the recipients are illegal immigrants, despite some going to the wrong people, his spokesman has said.

The Home Office says just 14 people out of a total of 58,800 contacted were mistakenly asked if they had overstayed their visas.

But campaigners say the true number of people wrongly contacted is far higher.

Labour described the government's tactic as "shambolic and incompetent".

Some people suspected of having outstayed their visas were sent a text reading: "Our records show you may not have leave to remain in the UK. Please contact us to discuss your case."

The prime minister's official spokesman acknowledged that the wording of the texts had changed since the campaign began.

Originally, they had included the phrase: "You are required to leave the UK as you no longer have the right to remain."

'Atmosphere of fear'

The Home Office said it was "right to enforce the rules", and Mr Cameron's spokesman said: "The prime minister agrees with the principle of the texts.

"It is one of various means the Home Office contacts people who may not have the right to remain in the UK."

But two recipients of the texts - campaigner Suresh Grover and immigration lawyer Bobby Chan - reacted angrily to the message.

To send threatening text messages and emails to people on some sort of clearly ill-managed central database is deeply disturbing Nigel Farage, UKIP leader

"I came here with my parents in 1966, I was born in East Africa and have a British passport," Mr Grover told the Independent newspaper - adding he was "shocked" and "horrified" to be contacted in this way.

Mr Chan said the texts "stereotype immigrants as a criminal community and create an atmosphere of fear".

But the Home Office defended its position: "We are taking proactive steps to contact individuals who records show have no valid right to be in the UK."

The individuals affected had been contacted in a variety of ways, including email and text, it added.

It also denied that Mr Grover had been contacted at all.

Mr Grover told the BBC he would instruct his lawyers to write to the Home Office, challenging its claim he had not received the text directly.

The department has received more than 140 complaints about the campaign, although Capita said: "Most complaints occurred in the early part of the contract where Capita was, as part of the contract, updating sometimes out-of-date Home Office records."

Capita believes that 4,160 people have departed the UK since December 2012 as a result as a result of being contacted, the Home Office said.

'Stupid and offensive'

Labour's shadow immigration minister David Hanson said: "Theresa May's immigration system lurches from one gimmick to another with little effect.

Image caption The adverts contained inaccurate arrest figures, the Advertising Standards Agency said

"The reports that the government has allowed a private contractor to send British citizens text message telling them to leave the country demonstrates once more just how shambolic and incompetent the Home Office's border police is under Theresa May.

"These messages will rightly cause distress and offence to British citizens, many of whom have done much to contribute to our society. It is simply wrong for this sort of message to be sent by text, and to be so poorly targeted."

UKIP leader Nigel Farage, who campaigns for tighter border controls and Britain's exit from the EU, said the text message scheme was the product of a government with "absolutely zero sensibility and even less sense".

"To send threatening text messages and emails to people on some sort of clearly ill-managed central database is deeply disturbing and the sort of behaviour one would expect from a fascistic police state, not a democratic and inclusive nation. Quite frankly it's abhorrent."

UKIP MEP candidate Amjad Bashir said: "I find it utterly repugnant that people like me, who may have been born abroad but who are passport-holding and hard-working citizens of the UK are being threatened by the government in this way."

Meanwhile, immigration minister Mark Harper has said that vans telling illegal immigrants in London to "go home or face arrest" could be deployed across the UK.

He told BBC One's Question Time that the government was assessing the results of the scheme, which was piloted in the capital earlier this year.

During July, they were driven around the London boroughs of Barking and Dagenham, Redbridge, Barnet, Brent, Ealing and Hounslow for a week.

Labour accused ministers of "borrowing the language" used by the National Front in the 1970s.

Lib Dem Business Secretary Vince Cable said the campaign had been "stupid and offensive".

Earlier this month, the Advertising Standards Authority (ASA) banned the posters, saying they had misled the public about the arrest statistics displayed.

However, it cleared the campaign of being offensive and irresponsible.

Mr Harper told Question Time: "I don't have any problem with saying to people who are here illegally that they shouldn't be here anymore."