DUBLIN, IRELAND (FT) — AerCap, the world’s biggest aircraft leasing company, has lost a bid to recover one of its planes leased to Aeroflot after a court in Sri Lanka ruled that the Russian flag carrier could fly the aircraft back to Moscow.

The Airbus A330-300 jet was detained at Colombo’s Bandaranaike International Airport last week as it was about to make a return flight to Moscow.

The detention followed an application for an injunction by Celestial Aviation Trading, a subsidiary of AerCap, to the Commercial High Court in Colombo.

The jet was detained pending a court hearing earlier this week, but the original order has since been lifted, and the aircraft left for Moscow on the same day, according to people familiar with the situation.

AerCap declined to comment.

The Dublin-based lessor originally asked for the wide-body jet’s return in February, days after the imposition of western sanctions on Russia following its invasion of Ukraine, according to court documents seen by the Financial Times.

The sanctions imposed on Russia triggered a global rush among overseas leasing groups to recover more than 500 aircraft, worth an estimated $10bn, that were stuck in the country.

International lessors had until the end of March to sever their ties with Russian carriers, but, despite doing so, the companies have struggled to recover their jets after the Kremlin moved to allow foreign planes to be re-registered in Russia.

Russian airlines have continued to operate many of them. In total, 6,899 flights were made to and from destinations outside the Russian Federation using aircraft owned by non-Russian lessors between March 1 2022, and June 6, 2022, according to an analysis by aviation consultancy IBA.

The most common journey— 34 percent of these flights —was between Russia and Tajikistan.

AerCap, which had the largest exposure to the country of any foreign lessor, said in March it had lodged an insurance claim of $3.5bn to cover the potential loss of its planes and engines that remain in Russia.

Before the war, the company had 135 aircraft and 14 engines on lease with Russian airlines, approximately 5 percent of its fleet by net book value. It has managed to remove 22 aircraft and three engines outside of Russia.

According to the court documents, AerCap made several attempts in writing to recover the A330 jet from Aeroflot, pointing out the carrier was in breach of its lease obligations. The documents underline the challenges lessors have faced as they seek to recover their aircraft.Russia suspended all international flights in March, but the aircraft resumed flights to Colombo in April.

Russia, which earlier this month suspended all Aeroflot flights to Sri Lanka after the aircraft was originally detained, said the country needed to receive guarantees that a similar incident will not happen again, according to reports by the Tass news agency.

Dmitry Peskov, press secretary of Russian President Vladimir Putin, said that “in order for the flights to continue, some weighty assurances must be obtained that the situation that happened quite recently and days later with the Aeroflot aircraft will not repeat,” according to the reports.