By Estelle Shirbon
LONDON, June 13 (Reuters) - A split in Britain's ruling coalition will be exposed on Wednesday when Liberal Democrats refuse to support Conservative Prime Minister David Cameron in a vote challenging his handling of a row over the government's attitude towards Rupert Murdoch.
Cameron's backing of a minister accused of pulling strings for the media mogul was under attack in a parliamentary motion by the opposition Labour Party.
The Lib Dems, junior partners to the Conservatives in the coalition government, plan to abstain in a public disavowal of the Conservative position, though the government is unlikely to lose the vote.
What started out last July as a scandal over phone-hacking by reporters at one of Murdoch's newspapers has escalated into a full-blown political storm because of a string of revelations about the government's dealings with the Murdoch media empire.
Lib Dem leader and Deputy Prime Minister Nick Clegg was due to be questioned on Wednesday morning at the Leveson Inquiry into press ethics, which Cameron ordered last year because of the hacking scandal. The prime minister himself is due to testify at the televised inquiry all day on Thursday.
Britain's most high-profile politicians, including three former prime ministers and several serving ministers, have already appeared at Leveson, as have Murdoch and editors past and present of his numerous British media outlets.
The inquiry has brought out into the open the close and often mutually beneficial relations between generations of British politicians and the Murdoch press.
The issue under discussion in parliament on Wednesday is the case of Jeremy Hunt, a Conservative minister appointed by Cameron in 2010 to rule on Murdoch's bid for full ownership of lucrative pay-TV company BSkyB.
Hunt replaced Vince Cable, a senior Lib Dem minister who was stripped of his responsibility for the BSkyB issue after he was secretly taped saying he had "declared war" on Murdoch.
The Lib Dems have been less involved with the Murdochs in the past than the Conservatives, partly because they were never previously in power and so attracted less media interest.
As a result, as some Lib Dems have seen the Murdoch saga as an opportunity to get one up on the Conservatives at a time when their own support has slumped.
Hunt had expressed public support for the bid at the time he was appointed, but both he and Cameron maintain that he put aside his personal view and was impartial in his handling of the bid. In the event, Murdoch abandoned the bid under public pressure at the height of the hacking scandal last summer.
But evidence given at Leveson by Murdoch's son James, who was running the British arm of the family conglomerate at the time of the bid, raised questions over whether Hunt was in fact too close and too helpful to the Murdochs, given his role.
Cameron has resisted calls to order an investigation into whether Hunt had breached the ministerial code of conduct, but Labour has refused to let go of the embarrassing issue.
Members of parliament (MPs) are scheduled to debate the Labour motion on Hunt at 1130 GMT, just after Cameron faces his weekly half-hour grilling by MPs and at a time when Clegg will still be testifying at Leveson.