Turkish port authorities have begun informally requiring shipping agents to provide letters declaring that vessels are not linked to Israel and not carrying military or hazardous cargo bound for the country, according to two shipping sources.
The move is another step Turkey has taken against Israel after it last year severed trade with the country, worth $7 billion annually, over its war in Gaza with Palestinian militant group Hamas.
The sources said the harbour master's office had verbally instructed port agents to provide written assurances, adding that there was no official circular on the issue.
One of the sources said the instruction applied to ports across Turkey.
The second source said vessels arriving directly from Israel or departing to Israeli ports would no longer be permitted to dock at Turkish ports, according to information provided by the port authority of the northwestern province of Kocaeli.
Turkish-flagged ships will also be prohibited from calling at Israeli ports, according to the source.
The transport ministry did not immediately respond to a request for comment.
The move could further complicate shipments to Israel in the Eastern Mediterranean. Yemen's Iran-aligned Houthis have targetted ships in the Red Sea since 2023 in what they call an act of solidarity with Palestinians.
NATO member Turkey has fiercely criticised Israel over its attacks on Gaza and called it a genocide against the Palestinians, a charge Israel denies.
The new guarantee letters should state that vessel owners, managers, and operators have no ties to Israel, and that certain types of cargo, including explosives and radioactive materials or military equipment, are not on board en route to Israel, the second source said.
Reporting by Can Sezer and Ezgi Erkoyun