(AFP) – Former British prime minister David Cameron was guilty of “gross negligence” in not having a contingency plan for Britain leaving the European Union, a parliamentary committee said Wednesday.

Former cabinet office minister Oliver Letwin earlier told the foreign affairs select committee that civil servants were not instructed to make plans for Brexit due to fears they would be leaked during the campaign, and that it would have been be impossible in any case given Cameron’s expected resignation.

Cameron’s “considered view not to instruct key departments including the Foreign Office to plan for the possibility that the electorate would vote to leave the EU amounted to gross negligence,” said the report.

Lack of planning had left the Foreign Office under-staffed and under-resourced, and facing the risk of losing more staff to new departments dealing directly with Brexit, it added.

The committee is chaired by Conservative MP Crispin Blunt and comprises 11 MPs from different parties within the House of Commons.

“While it is essential that the Whitehall officials with relevant expertise are identified and put at the centre of managing the exit process, this cannot come at the expense of an already-overstretched FCO,” the report added.

“This is also about the UK’s international reputation. Our security, prosperity, values and democracy will depend on the strength of these key departments and their working relationships.”

Letwin told the committee that preparatory work to get the civil service ready for the new workload could be achieved by September.

“If you are asking the practical question, ‘Would it have been possible to pre-design the strategy for negotiation?’ the answer is that as things have turned out it would not have been possible,” he said.

“I believe it is actually possible to do the work and preparation we are doing in the period between now and 9 September. It is hard work, but I think we can do it.”

The ministry is now headed by Brexit figurehead Boris Johnson following his surprise promotion be new Prime Minister Theresa May.