Fifty US nuclear weapons stored at a Turkish airbase at Incirlik are at risk of being stolen by terrorists, a Washington-based think-tank has said in the wake of Turkey's attempted coup in July.

The report has claimed that the dozens of nuclear weapons held some 110km from the Syrian border could be compromised, putting the US's nuclear assets at risk.

It said leaving them at the base, which is a crucial strategic point for coalition forces carrying out airstrikes against Isis, was "a roll of the dice" after the facility's Turkish commander was arrested for his suspected involvement in attempting to overthrow the country's leading AKP party.

"Whether the US could have maintained control of the weapons in the event of a protracted civil conflict in Turkey is an unanswerable question," the report from the Stimson Center said.

"From a security point of view, it's a roll of the dice to continue to have approximately 50 of America's nuclear weapons stationed at Incirlik," one of the authors of the report, Laicie Heeley told AFP. "There are significant safeguards in place. But safeguards are just that, they don't eliminate risk. In the event of a coup, we can't say for certain that we would have been able to maintain control" she added.

The Pentagon has said it will not comment on its nuclear arrangements. The bombs are kept at the base strategically as a deterrent to Russia as part of the Nato alliance. Turkey hosts Washington's largest overseas nuclear weapons stockpile, all of them are believed to be stored at the Incirlik.

The publishing of the report comes at a particular low-point in relations between Washington and Ankara, in the wake of last month's failed coup attempt. Erdogan has called for the US to extradite cleric Fethullah Gulen, whom he accuses of being behind the uprising.

In a symbolic reset in international relations between Russia and Turkey, Erdogan met Putin in St Petersburg on Tuesday (9 August), leading to a pledge of increased security cooperation. The two countries had been at loggerheads since November, when Turkey shot down a Russian warplane in northern Syria.

However, Nato has said there is no risk of Turkey leading the alliance, despite rapprochement with Moscow. In a statement on 10 August, Nato spokeswoman Oana Lungescu described Turkey as a "valued ally, making substantial contributions to Nato's joint efforts".