The chancellor, George Osborne, is facing pressure to appear in person before the Leveson inquiry into media ethics to explain his role in the appointment of former News of the World editor Andy Coulson as David Cameron's communications chief.
It emerged on Friday that Osborne, who is understood to have persuaded Cameron to take on Coulson in July 2007 in order to sharpen up the Tories' press operations, would only be submitting a written witness statement.
Cameron and several cabinet ministers, including business secretary Vince Cable, culture secretary Jeremy Hunt, justice secretary Kenneth Clarke and education secretary Michael Gove, are all expected to appear in person.
Paul Farrelly, the Labour MP who sits on the department of culture, media and sport select committee, and who has been one of the leading critics of News International and its political influence, said Osborne should appear to explain the appointment.
"The recruitment of Andy Coulson to 10 Downing Street was clearly a colossal mistake. George Osborne was instrumental in that deployment," he said.
Coulson, who was taken on by Cameron having quit as News of the World editor after one of its journalists was jailed in 2007 for phone hacking, will appear before the Leveson inquiry on Thursday. He moved with the prime minister to Downing Street in May 2010 after the general election, eventually resigning in January 2011. Rebekah Brooks, the former News International chief executive, will appear on Friday.
Farrelly said Leveson could summon Osborne. "It's really important that this inquiry gets to the bottom of politicians' links with the press, including the Murdoch empire. George Osborne really should be examined in person about the reasons he felt Andy Coulson was an appropriate person to become the PM's chief of communications."
Farrelly pointed out that before he resigned, Coulson had been at No 10 for seven months while News Corp's buyout of BSkyB had been on the cards.
Lib Dem peer Lord Oakeshott, who tabled parliamentary questions about Coulson's appointment, also said Osborne should appear. "George Osborne recruited Andy Coulson to a key role at Cameron's right hand and worked with him every day at the heart of government. Nothing happens in No 10 or No 11 without Osborne's say so," Oakeshott said. "Leveson without Osborne would be like Hamlet without the prince."