The Kremlin has “stolen” more than 150 foreign-owned commercial planes since Russia invaded Ukraine, by re-registering the jets.

State-backed Russian airlines have been accused of transferring aircraft to the country’s own registry without the approval of their owners.

Experts say that around three-quarters of the re-registered aircraft were flying as recently as last week.

Russian airlines had 980 jets in service in March, according to analytics firm Cirium. Some 777 were leased, two-thirds of which were rented from foreign leasing companies based in Ireland and Bermuda.

Some 360 aircraft have been added to the Russian register since the start of March, of which 171 are owned by non-Russian leasing companies.

Vladimir Putin announced new laws last month allowing Russia to hold foreign-owned aircraft hostage. On March 14, the Kremlin suspended the “Cape Town Treaty”, that was designed to make the legal repossession of aircraft more efficient in foreign jurisdictions.

Aviation consultancy IBA Insights, which compiled the re-registration figures, said the unilateral re-registration of the planes “violates international law”.

Phil Seymour, president of IBA Aviation, said the aircraft had effectively been “stolen by the Russian Federation”.

He added: “By putting these aircraft on the Russian register, it means that the Russians have taken control of these aircraft.”

Mr Seymour said that the re-registering of aircraft would be likely to trigger insurance claims by the leasing companies that own the planes.

Dublin-based Aercap, one of the world’s biggest leasing companies, has already lodged a $3.5bn insurance claim for aircraft that are trapped in Russia.

IBA said that Aercap was the worst hit by the Russian actions, with 49 aircraft re-registered.

Lloyd’s of London chief executive John Neal has sought to play down the insurance market’s exposure to an estimated $10bn (£7.8bn) of claims in relation to aircraft that are being held hostage.

He said in March that the underwriters may only need to pay out as little as 15pc to 20pc of the value of the aircraft.