Britain's data watchdog confirmed today it was investigating complaints of immigration officials' shoddy records which saw people wrongfully ordered to leave the country.
The Information Commissioner's Office said it had opened an initial inquiry into the botch-up, which involves a £40 million UK Border Agency contract with privateer Capita.
The "business process outsourcing" specialist has been paid to contact around 174,000 people in Britain whose records show their right to remain has expired.
But the red-faced agency admitted at least some of its records were inaccurate and outdated after immigration lawyers said this week they had heard several cases of Capita instructing people to leave the country when they had every legal right to stay.
It is believed the total number of people wrongly threatened could run into the hundreds, with some called or messaged several times a day.
Under the Data Protection Act the agency is obliged to ensure its personal records are factually accurate and up-to-date.
A spokesman for the commissioner's office said it was important that any organisation take reasonable steps to abide by the Act.
"If anyone feels that an organisation has not handled their information fairly then they can make a complaint to the Information Commissioner's Office."
A Border Agency spokesman said it was only "a small number" of people who had been wrongly warned.
But the agency was mindful of the importance of data protection, he added.
A spokeswoman for Capita later said the company had not been contacted by the ICO.