Eurasia Review - Turkey has closed its ports to Iranian oil, fully complying with U.S. sanctions against its main supplier, despite Ankara publicly criticising the United States� move to end import waivers and warning of a struggle to tap alternative producers.

The U.S. decision to fully re-impose sanctions on Iranian oil ended a six-month reprieve for Turkey and seven other big importers as Washington steps up attempts to isolate Iran and choke off its oil revenues.

An American military presence in the region has also raised concerns over a potential U.S.-Iran conflict.

Full compliance allows Turkey to avoid U.S. sanctions even as its ties with the NATO ally are strained on several other fronts, including over the planned purchase of a Russian missile defence system that would trigger separate U.S. penalties.

Turkey�s largest oil refiner Tupras had pressed Washington for an extension of the import waiver before the May 1 expiration, according to a person familiar with the talks, adding that when it was not granted the company made it clear it would halt all imports from Iran.

Tupras did not immediately reply to a Reuters request for comment.

According to Refinitiv tracking data, no tankers loaded in Iran have arrived at Turkish ports so far in this month.

Four days after the waiver ended, a tanker carrying 130,000 tonnes of Iranian crude was midway across the Mediterranean Sea to Turkey when it changed course and turned off its tracker, Refinitiv oil analyst Ehsan ul-Haq said. Analysts, citing satellite imagery, said it likely unloaded instead at the Syrian port of Banias.

The data shows that Turkey began trimming its Iranian imports as early as march. Analysts said it has replaced the oil from its neighbour with oil from Iraq, Russia and Kazakhstan.