A leading conservative voice for climate change has claimed the Treasury is “at war” with the Department for Energy and Climate Change (DECC), leaving Britain without a clear energy policy.

Speaking at an IPPR event on the implementation of Europe’s energy union – a day before Amber Ruud’s speech outlining the UK’s energy strategy – Sir Crispin Tickell, former UK ambassador to the United Nations, asked for clarity on plans for UK energy “given the state of war between the Treasury and DECC at the moment.”

He added: “The evidence of the war between the Treasury and DECC is ridiculous, at the moment Britain doesn’t seem to have an energy policy.”

Since the Conservative government was elected in May, DECC has seen a number of its policies reduced or cut in an effort to reduce public expenditure. DECC has also seen its budget for 2015/16 cut by £70m as well as agreeing to a circa 21% budget cut by 2020.

The formation of the National Infrastructure Commission (NIC), which will be responsible for addressing the UK’s future energy needs and is answerable to the Treasury, has also been regarded as a Treasury landgrab over DECC’s energy portfolio.

Tickell, who was credited by Margaret Thatcher in 1988 for persuading her to make a speech on global climate change to the Royal Society, has also published a blog post for Conservative-supporting blog Conservative Home discussing the role of Treasury in dictating low carbon policy. In it, he claims: “We have seen the dark hand of the Treasury reducing expenditure on low carbon sources without apparent regard to the implications for climate change.”

Tickell believes the apparent move away from environmental policy towards other forms of energy generation, such as nuclear and gas, has left the UK without a credible climate change policy.

In the context of the upcoming climate change summit in Paris, Tickell added in his online post that this is the worst time for the UK to be cutting its carbon reduction efforts.

“The lead-up to the Paris summit that may see a global climate agreement signed is the worst time to be eliminating sensible measures that cut energy waste and stimulate the building of low-carbon energy systems. [International] respect will be much diminished if the prime minister allows his chancellor to undermine our own progress on reducing emissions.”

Tickell has urged the government to focus on a policy of reducing energy use over the development of alternative sources. He claims ‘ambitious and evidence-based policies that cut energy waste and make each watt that we use more productive’ are needed.