One more tanker took to 20 on Friday the number of vessels waiting in the Black Sea to pass through Istanbul's Bosphorus Strait on the way to the Mediterranean, the Tribeca shipping agency said, amid talks to disperse the build-up. On Thursday, dismissing pressure from abroad over the lengthening queue, Turkey's maritime authority said it would continue to keep out of its waters oil tankers that lacked the appropriate insurance letters, and it needed time for checks. Eight tankers were also waiting for passage through the Dardanelles strait into the Mediterranean, down from nine a day earlier, Tribeca said, making a total of 28 tankers waiting for southbound passage, according to Reuters. The G7 group of nations, the European Union and Australia have agreed to bar providers of shipping services, such as insurers, from helping to export Russian oil unless it is sold at an enforced low price, or cap, aimed at depriving Moscow of wartime revenue. In a telephone call on Wednesday, US Deputy Treasury Secretary Wally Adeyemo told Turkish Deputy Foreign Minister Sedat Onal that the cap applied only to Russian oil and did not necessitate additional checks on ships crossing Turkish territorial waters, the US Treasury Department said. However, Turkey has had a separate measure in force since the start of the month, which is causing a logjam. It requires vessels to provide proof of insurance covering the duration of their transit through the Bosphorus strait, or when calling at Turkish ports. It said it could remove tankers without proper documentation from its waters or require them to furnish new P&I insurance letters covering their journeys through its territory.