Cameron defends decision to block top civil service appointment
Climate change expert David Kennedy did not have enough "commercial experience" to be the energy department's top civil servant, David Cameron has suggested.
Asked about his decision to veto the appointment, the PM said it would be "wrong" to comment on individual cases.
But he went on to explain how "the ability to do deals" was vital to help the department "sell" its policies.
He also said the government should have an "open mind" on the process of obtaining shale gas known as fracking.
The Department of Energy and Climate Change (DECC) is renewing its search for a permanent secretary after the PM took the unusual step of vetoing the choice of an independent recruitment panel.
Mr Kennedy is currently chief executive of the independent committee on climate change, an advisory body to the government.
"The most important thing we need now in the Department of Energy and Climate Change is actually commercial experience, the ability to do deals," the prime minister told the Commons Liaison Committee, which is made up of senior backbench MPs.
"I want to see wave upon wave of investment coming into Britain to build our nuclear-power stations, to invest in the North Sea, to build green tech, green jobs, green investment.
"Now we've got a determined energy policy, let's get out there and sell it to the rest of the world. That's the priority."
Mr Cameron also described fracking as a "gas revolution" which could be "really quite transformative", leading to lower energy bills.
"That may be true, that may not be true. We just don't know. But I think it would be a big risk just to ignore what is happening in the gas market.
"We should have an open mind and we should take part in fracking and unconventional gas because this might be a revolution that we should be involved in," he said.
Fracking involves pumping water and chemicals into shale rock at high pressure to extract gas.
It is widely used in the US, but it was temporarily banned in the UK after being blamed for two earth tremors in Blackpool in 2011.
In an earlier section of the committee hearing focused on policing and justice, Mr Cameron said government plans for secret court hearings were "not a massive departure" from the status quo.
The government wants some civil cases involving sensitive information, which would otherwise have to be settled out of court, to be heard in front of a judge.
It argues that it is currently impossible for it to defend itself against cases of alleged complicity in torture in open court as the disclosure of sensitive information could endanger British agents and compromise relationships with key allies.
The PM said secret hearings would only be needed "in a small number of cases".
But opponents say the proposals, contained within the Justice and Security Bill, compromise the principle of open justice.
The bill suffered three defeats in a single day last month, amid widespread opposition in the House of Lords.
Mr Cameron told the committee he knew the proposals would be controversial and indicated he was prepared to make changes to the legislation without abandoning its central purpose.
Commenting on Mr Cameron's evidence to the committee, pressure group Reprieve's Clare Algar said: "The origins of this bill clearly lie in a desire to avoid government embarrassment."
She called on the government to "list which cases it is that require such a dangerous departure from the proud British tradition of fair and equal justice".