By Peter Mulligan
BBC parliamentary correspondent
Former ministers questioned the Tory stance on energy
It was day two of a marathon debate over the Lisbon Treaty on EU reform.
This time, the issue of the agenda was its effect on energy policy.
And, with both Labour and the Lib Dems supporting the treaty, the debate was more notable for differences of opinion among the Conservatives.
Shadow business secretary Alan Duncan faced some sceptical questioning from senior figures on his own side.
Former environment secretary John Gummer said: "If every nation takes the view that it won't do anything on energy unless it has total control over its own, then we won't be able to meet our energy needs."
Mr Duncan replied: "I'm all for the co-operation advocated by my right honourable friend, but not for the transfer of power that allows us to be told to do things that are unclear in the wording of this treaty."
He went on to suggest that parts of the treaty posed an open-ended risk to the UK.
Mr Duncan said: "It could give rise to the setting up of an EU regulator. It could potentially allow the EU to tell us what we can and cannot do with our nuclear power stations.
"It could even lead to decisions over whether or not we have the Severn barrage."
This brought another Tory intervention, this time from the highly sceptical former chancellor Ken Clarke.
He asked: "How on earth is this giving powers to Europe to veto the Severn barrage or determine what sources of energy we use? It explicitly says that is not the case."
Mr Duncan explained: "Whereas one begins by thinking these will be benign powers granted to the EU, they normally morph into something completely different.
"And what we are seeking here is clarity, in the belief that the powers that already exist are sufficient."
'Protect and secure'
For the government, Business Secretary John Hutton began by saying the treaty would help speed the liberalisation of the energy market in Europe.
It was true, he admitted, that the government harboured concerns, but these had been dealt with.
Mr Hutton said: "Firstly we are able to protect and secure our rights over our national oil and gas reserves.
"Secondly we can act to ensure we will always ensure supply during in emergencies.
"And any new article will not impede progress in opening up EU markets and liberalisation. The concerns have been addressed."
Looking across the chamber during the debate, Mr Duncan detected a smirk.
He said: "The minister can well laugh and this is the deceit that the whole country gets so angry about that ministerial assurances - if that's what that chuckle meant - count for so little.
"Because in the end it's the words in the treaty that matter, not the scoffing of the minister."
For the Liberal Democrats, Steve Webb also welcomed the treaty, saying European countries had to work together.
The European marathon continues.