DUBAI, United Arab Emirates (AP) — A United Kingdom maritime organization says a ship reportedly has been boarded by armed men off the crucial Strait of Hormuz.

The United Kingdom Maritime Trade Organization said in an alert Tuesday night that the vessel “had been boarded by armed men while at anchor” near the strait off the coast of Iran.

The organization offered no further detail. The U.S. Navy’s Bahrain-based 5th Fleet did not immediately respond to a request for comment. There was no immediate report from Iran on the incident.

The U.K. organization urged ships traveling in the area to “exercise caution.”

The incident comes amid heightened tensions between Iran and the U.S. A maritime intelligence firm warned of suspicious incidents near the strait in recent weeks.