David Cameron has emerged as a frontrunner to be the next secretary general of Nato after reports he will be nominated by Theresa May.

The former prime minister is reportedly being lined up by the UK Government as a candidate to replace the current secretary general, former Norwegian prime minister Jens Stoltenberg, when he steps down in 2018 or 2019.

Michael Fallon, the Defence Secretary, has previously said the UK will play a bigger role in Nato to make up for its withdrawal from the EU.

Cabinet sources said they want to find a prominent role for Mr Cameron, who resigned in June after losing the EU referendum.

One senior Cabinet minister told the Daily Mail: “We’ve got to find a role for him – he has so much to offer. We have got to get him batting for Britain again.”

Allies of Mr Cameron suggested he would be interested in the role. One said: “The key at this stage is to flag high-level interest in leader level conversations and to show that our eventual candidate is visible and acceptable to everyone.

“That means a would-be candidate would need to start talking about the right issues and show up at various conferences such as the Munich Security Conference and Davos.”

Key to winning the position will be securing the support of the United States. The secretary general is appointed by consensus after discussions between the 28 Nato member states, but American support is seen as important in influencing other states.

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Nato’s most senior military officer, the Supreme Allied Commander Europe, is usually an American and so the secretary general of the organisation has traditionally been an European. The last Briton to hold the post was George Robertson, a former Labour Defence Secretary, between 1999 and 2003.

Earlier this year Mr Fallon said the UK wanted to step up its involvement in Nato. He said: “It’s a disappointment we’re leaving the European Union because in my view it does add to what Nato gives us. But Nato is the cornerstone of our defence and what we'll be telling other leaders is we'll be doing more in Nato to compensate for our withdrawal from the EU.

“We’ll be leading harder into the alliance and that’s the purpose of the deployments we’re announcing today.”

Mr Stoltenberg began his term in 2014, succeeding former Danish prime minister Anders Fogh Rasmussen.

What will David Cameron do next?

The post comes with a £220,000 salary.

Mr Cameron is currently on the speaking tour circuit. where he is reported to be earning hundreds of thousands of pounds per speech.

He is also in the process of writing his autobiography, due to be published in 2018.

The next head of Nato is likely to take office at a key time for the organisation. US President-elect Donald Trump has been critical of the organisation and said he would make US contributions to Nato dependent on other states paying a bigger share.

Mr Trump said he would not necessarily come to the defence of a Nato ally under attack – the core promise of the alliance.