Tony Blair will appear before the Leveson inquiry into press ethics on Monday, it has been announced.
The former Labour prime minister is likely to be quizzed over whether he was too close to Rupert Murdoch and News International during his time in office.
On Monday Lord Mandelson acknowledged that both Blair and his successor Gordon Brown "arguably" became "closer than was wise" to Murdoch.
But the former Labour business secretary and other senior Labour figures have repeatedly denied that Blair made a formal deal with the Murdochs promising to legislate in a way they wanted in exchange for favourable press coverage.
Blair's former chief spin doctor Alastair Campbell told Leveson this week: "I don't think on policy anything was ever traded with Rupert Murdoch or with any other media owner."
However Labour MP Tom Watson told the inquiry that ministers in Blair's government, were scared of how they were portrayed in the Murdoch tabloids.
"There was a mystique about the News International stable, that they had unique access to Downing Street," he said.