The Government’s infrastructure tsar has slammed its bungling of the Crossrail 2 project and warned that Britain’s “historic weakness” in strategic infrastructure planning risks scuppering its post-Brexit growth.

The first report from the National Infrastructure Commission (NIC) branded progress on South East England’s mega rail project “hugely disappointing” and also heaped criticism on the pace of progress for the Northern Powerhouse Rail and Heathrow expansion projects.

Sir John Armitt, who replaced Andrew Adonis as NIC chair last month, called for urgent government action within the coming months to avoid damaging Britain’s economic growth and international competitiveness.

“It is hugely disappointing that nearly two years after the Commission’s reports on Crossrail 2 and Northern Powerhouse Rail, the Government still has not firmly committed to a timetable or a clear plan for delivering either of these nationally significant projects,” he said.

He said it is vital that decisions are taken on both rail projects before the end of the year, and added it is imperative that ‎a parliamentary vote on the expansion of Heathrow takes place no later than this summer.

“Any further delay would be irreconcilable with the Government’s commitment to deliver the infrastructure the country needs,” he said.