Russian airlines could be forced to re-register their aircraft in their homeland, which would cut the Bermuda registry by 75 per cent.

Thomas Dunstan, director-general at the Bermuda Civil Aviation Authority, said the majority of the aircraft on Bermuda’s registry were based in Russia.

He warned that if the Russian Government did decide to insist the country’s aircraft are registered in the country, it would cause a major loss of revenue for Bermuda.

But Mr Dunstan said the BCAA had a plan to diversify the register in the event that Russia does follow through on the threat.

Mr Dunstan said: “This gets raised by the Russian Government quite regularly — at least once a year.

“The reality is that moving this number of aircraft from the Bermuda registry would be a multiyear process requiring a lengthy transition period.”

A spokeswoman said the BCAA was working to expand the Bermuda registry to aircraft in jurisdictions that are signatories to the ICAO Convention on Civil Aviation such as Azerbaijan, Tajikistan and Saudi Arabia.

She said: “We are also making a concerted effort to expand our private aircraft registry in the Asia region.”

Russian airlines have normally registered Western-built aircraft in countries such as Bermuda and Ireland, partly to avoid import tax.

As of October 31, there were 736 Bermuda registered aircraft operating for Russia airlines, all of which were built outside Russia.

According to Government, the total annual revenue of the BCAA is about $30 million.

Aleksander Yurchik, the Russian Deputy Minister of Transport, said at the Wings of the Future conference in Moscow last month that the decision to require the re-registration of planes in Russia had already been made.

He said: “We are very capable to maintain airworthiness in this country.

“I expect that at the end of the transitional period a lot of non-Russian carriers will want to register their aircraft here.”