Türkiye on Tuesday hailed an agreement it said was reached with its counterparts allowing for the continuation of a new regulation requiring crude oil tankers to present an insurance confirmation letter before transiting the Turkish Straits.

The Turkish measures that have been in force since the start of this month require vessels to provide proof they have insurance in place for all circumstances covering the duration of their transit through its straits or when docking at Turkish ports.

A line of around 20 oil ships had been waiting in the Black Sea last week, as they worked to present the necessary documents.

The regulation came before the European Union and the Group of Seven (G-7) leading industrialized nations agreed earlier this month to block Western firms from servicing ships that sell Russian oil for more than $60 a barrel.

The decision was part of a U.S.-led drive to punish Russia for its war on Ukraine by stripping away its main source of income while avoiding major disruptions to the global crude market.

But Türkiye voiced alarm over the possibility of uninsured ships passing through the Bosporus – a strait running through the heart of the 16-million-strong city of Istanbul.

Türkiye’s Maritime Authority on Tuesday said that 22 of the 26 crude oil tankers that arrived at the Bosporus had presented the necessary letter, and 19 of them had already transited the strait.

Four ships are still waiting in the Black Sea and authorities are still awaiting an insurance confirmation letter before allowing them to pass through the Bosporus, which bisects Istanbul, it added.

"It is pleasing that the talks we have been holding with our counterparts have concluded with the acceptance of our new regulations that will protect the Turkish Straits and that maritime trade continues as ordinary," the maritime authority said.

Western insurers had suggested the regulations would mean they would have to provide cover even in the event of the ship being in breach of sanctions against Russia, which is something they were not prepared to do.

European diplomats have been meeting with insurers and Turkish officials in a bid to agree on a compromise text that could suit all parties.

The revised letter template reported by Reuters showed the wording had changed, which indicated that insurers would not bear liability in all circumstances.

Industry sources said the new template had already been used by some of the Western insurers to enable some of the tankers that were stuck to pass.

The average waiting time at the Bosporus for southbound tankers fell to 2.9 days to 3.4 days from 3.8 days to 4.3 days on Monday, the Tribeca shipping agency said. The average waiting time peaked at above six days last week.

Millions of barrels of oil per day move south from Russian ports through Türkiye’s Bosporus and Dardanelles straits into the Mediterranean.

Considering their vital commercial importance as they connect the Black Sea with the rest of the world, the two straits became a major point of discussion with the eruption of the Russia-Ukraine war on Feb. 24.

The passages are among the world’s most difficult waterways to traverse, as ships must deal with strong currents, sharp turns and varying weather conditions.

The 1936 Montreux Convention guarantees freedom of navigation for merchant vessels passing through Türkiye’s two waterways. But it also gives Ankara the right to regulate security – the provision it is applying to make sure the oil ships are insured against spillage and other accidents.

The bottleneck in the straits had made little impact on the global oil market because most Western countries no longer purchase Russian crude.

An analysis by Bloomberg showed that Bulgaria was the only European country to have imported Russian oil this month. It showed most of the Russian tankers now headed for Asian markets through the Suez Canal.