David Cameron's military policy failures mean he must be ruled out of the running in the race to become the next Nato chief, the Tory chairman of the Defence Select Committee has said.

The former prime minister is a man of “charm and ability” but lacks the wisdom to take on the role of Nato Secretary General, according to Julian Lewis.

Mr Cameron has been tipped as a possible replacement for current post-holder Jens Stoltenberg, whose term is due to end within the next two years.

But Mr Lewis said the ex-premier's military intervention in Libya, which MPs have since criticised for lacking a coherent strategy, as well as his decision to drastically cut troop numbers and claim that Brexit could put peace in Europe at risk, meant he was not the right man for the job.

In a speech as part of the Speaker's Lecture series, Mr Lewis said: “During the Christmas recess, an obviously planted story appeared in a tabloid newspaper suggesting that our most recent former prime minister should be the UK's candidate as next Nato Secretary General.

“It was duly taken up by the wider media, with heavy hints suggesting that No 10 was actively considering the proposal.

“David Cameron is a man of charm and ability. He deserves to find a role commensurate with his talents, and I am sure that he will; but those talents do not include wisely judging strategic issues, whether when toppling Arab dictators in places like Libya, increasing military commitments whilst cutting the Armed Forces, predicting a Third World War in consequence of Brexit, or dangerously delaying the renewal of Trident for the sake of Coalition politics - as he did.”

In an interview with The Times, Donald Trump branded Nato “obsolete” but also said the military alliance was “very important” to him.

Mr Lewis warned that if the US turned away from organisation, Europe would have “little chance” of deterring non-nuclear threats.

But he claimed the US president-elect was trying to strengthen the alliance by confronting the “free-riders” who failed to spend more than 2% of GDP on defence.

Mr Lewis said: “It seems to me far more likely that, by confronting the 'free-riders' within the Alliance, he actually aims to strengthen Nato by ensuring that all its members properly fund their armed forces in the future.”

Mr Lewis also renewed his calls for reforms to stop troops facing prosecutions over action during The Troubles, insisting any system that allowed legal aid to be used as a “weapon” against its own personnel had “surely taken leave of its senses”.

He called for a statute of limitations to cover incidents in Northern Ireland that took place before the Belfast Agreement to be introduced to restore “some semblance of justice and fairness” to the process.

Without protection, hundreds of veterans face court action while “amnestied terrorists - including mass murderers - freely walk the streets of Ulster”, he said.