Home Secretary Jacqui Smith today denied there had been any cover-up over the employment of illegal immigrants in the security industry, insisting ministers had taken "robust action".
In a Commons statement, Ms Smith stressed it was the "legal duty" of all employers to ensure that their employees were entitled to work in the UK.
The Security Industry Authority, which has licensed applicants for security posts since 2003, had "not failed to do anything that it was obliged to do in law".
She told MPs that from July every non-European applicant had had their right to work in the UK checked and from October the SIA had required "new and tighter" identity checks.
"My approach was that the responsible thing to do was to establish the full nature and scale of the problem and take appropriate action to deal with it, rather than immediately to put incomplete and potentially misleading information in to the public domain."
But shadow home secretary David Davis said the Home Office response so far to the disclosure that thousands of illegal immigrants were cleared to work as security guards had been "blunder, panic and cover-up".
The latest row erupted after documents obtained by the Daily Mail apparently showed that Ms Smith was made aware of the problem involving at least 5,000 illegal immigrants as early as July - four months before the news became public last weekend.
Press reports at the weekend revealed that some illegal immigrants given licences by the SIA ended up working for the Metropolitan Police. Others reportedly found employment in Whitehall and at ports and airports.Reuse content