A “relentless focus” on implementing measures to help the economy must accompany cuts to public spending to reduce the deficit, the Prime Minister’s spokesman said.

With three weeks left before the Budget, the Cabinet met specifically to discuss growth. Unusually, implementing growth plans was the only item on the agenda.

Speaking at a regular Westminster briefing, the Prime Minister’s spokesman said Mr Cameron and Mr Osborne had “exhorted” their colleagues to focus on injecting energy into the economy.

“The economic situation and the economic challenges facing the UK are the top priority,” the spokesman said.

“That means sticking firmly to our plans to reduce the deficit but it also means a relentless focus on growth and measures to support growth.

“It is very easy for government to unveil and announce new policy initiatives. What is much more difficult is implementation.”

He set out areas of particular concern, including regulations for business, problems with the planning system, the tendency for EU directives to be “gold plated” when they are implemented in this country.

Government and other parts of the public sector can be concerned about the possibility of policies being open to legal challenge, slowing down progress, the spokesman said.

“It is difficult to get big infrastructure projects off the ground, whether in the public or the private sector. That is very difficult to make happen,” he said.

“The point is that all government departments, all Cabinet ministers, need to be challenging that kind of culture. It is the job of Cabinet ministers, the job of government to show real political will and push these things through.”

Mr Osborne, Oliver Letwin, the Cabinet office minister and Mr Cameron’s policy adviser, and Nick Clegg all spoke at length during the discussion.

The spokesman also confirmed that details of the government’s planning law reforms would be published “soon”.

“Reform of the planning system is a key part of what we are doing to boost growth,” he said. “We set out the principle of a presumption in favour of sustainable development. I think we will be setting out our plans on that quite soon.”