George Osborne was dragged deeper into the furore over the Murdoch empire's links to government as it emerged that he entertained Rebekah Brooks for a weekend at his country residence as Rupert Murdoch was planning to take over BSkyB.

Also present for the weekend at Dorneywood, the chancellor's grace and favour residence in Buckinghamshire, was Brooks's friend, Andy Coulson, the former News of the World editor, who at the time was working as David Cameron's director of communications inside No 10.

Labour said that the gathering, at a time when the government was evaluating how to react to News Corp's £8bn bid for the whole of BSkyB – the biggest in UK media history – raised fundamental questions about Osborne's judgment.

News of the weekend gathering will also increase pressure for Osborne to appear in person at the Leveson inquiry, in addition to David Cameron, culture secretary Jeremy Hunt, education secretary Michael Gove and other senior political figures, to answer questions about their links with the Murdoch team.

So far Osborne has been asked only to give written evidence, although his aides said he would now be happy to appear if asked.

Details of the Dorneywood sojourn are contained in a lengthy written statement to the Leveson inquiry submitted by Coulson, who appeared before it on Thursday. Listing his meetings with Brooks during his time working for Cameron, Coulson said: "My family and I also spent a weekend at Dorneywood in 2010 as a guest of George Osborne and his wife. Rebekah and her husband were also guests."

Osborne has made public four meetings with Brooks during 2010, three of them definitely after the May general election. A spokesman for Osborne said he believed the Dorneywood meeting was one declared by Osborne as having taken place with Brooks in September 2010. The location was not specified, and it was listed by the chancellor as having been a merely "social" event.

News of the Murdoch plan to take full control of BSkyB first broke in June 2010, with News Corp informing the European commission in early November of its intention to buy the shares it did not already own.

Giving evidence to the inquiry on Friday, Brooks said that, after briefly discussing the BSkyB bid with Cameron at a dinner in December 2010, she had a more substantial conversation with Osborne at a restaurant that month.

The next day she emailed News Corp lobbyist Frédéric Michel saying that Osborne had expressed "total bafflement" at Ofcom's latest response to the bid. But she was not asked, when in the witness box, about the weekend at Dorneywood or what was discussed there.

Harriet Harman, Labour's deputy leader, said the revelation raised serious questions. "When senior members of a government are looking at a bid such as the BSkyB one they have not only to make sure they act impartially but that they are seen to be acting impartially.

"Spending a weekend together with a senior executive of the company seeking approval for a bid such as this is not acting in a way that will be seen to be impartial." Osborne's aides said no discussions of the BSkyB bid took place.

But Labour MP Chris Bryant, a prominent critic of News International over phone hacking, said: "After all these revelations it feels like there were two halves of a single clan: in the political wing were Osborne, Cameron, Michael Gove and Jeremy Hunt, and in the media wing were Rebekah Brooks, James Murdoch and Andy Coulson. They seem to have been completely blind to the ethical considerations and to have forgotten that in government they are there for the whole country and not just for the clan."

Labour also plans to raise questions about whether the home secretary, Theresa May, sent a message to commiserate with Brooks after she resigned. In a speech to the Blairite pressure group Progress, Labour leader Ed Miliband renewed calls for the culture secretary to resign over suggestions he operated a secret back channel to News Corp.

Miliband said: "One of the reasons so many people hate politics so much right now is that they think politicians stand up for the wrong people, not the right people. This is a clear example of that – Jeremy Hunt was standing up for Rupert Murdoch, not for the public interest."