Prime Minister David Cameron agrees with the principle of the Home Office text messages urging people to contact them about their immigration status.
A Downing Street spokesman said: "The point of the texting, which the Prime Minister does agree with, is to get in touch with people who may be here illegally and to say to them ... that they need to be considering going home voluntarily or being removed.
"The principle of the text message is correct. This is one of various means the Home Office uses to get in touch with people who are here illegally to bring about their removal from the UK.
"It's a tiny proportion of texts that may have gone to erroneous people and the wording of the text just says 'you may be here illegally'."