"Speaking in the Commons, attorney general Dominic Grieve said pursing criminal charges could push back an investigation, although the joint-committee is likely to push ahead on the basis of continued legal advice.
The news came amid a temporary ceasefire between George Osborne and Ed Balls, after the chancellor admitted his counterpart was not directly involved in the Libor scandal.
The admission came just hours after Balls had challenged Osborne to apologise to him in the Commons, saying: "If he has any evidence he must produce it now.
"If he will not provide the evidence now he needs to stand at this despatch box now and withdraw this accusation."
The chancellor refused too back down in the Commons but hours after the debate his aides told sources at the BBC that Balls had not directly intervened in the affair"
From...
http://www.politics.co.uk/news/2012/07/06/burying-the-hatchet-osborne-retracts-balls-accusations
Might this explain why the accusation was made....
"...The chancellor's decision to personally involve Balls made cross-party consensus even harder to achieve than it was before, hijacking his own attempt to force through a joint-parliamentary inquiry..."
From the same article.