LONDON - A container ship was fired upon by an Iranian gunboat off the coast of Oman on Wednesday, damaging the vessel's bridge, the United Kingdom Maritime Trade Operations (UKMTO) said in a report.

The ship's master reported that a gunboat believed to be linked to Iran's Islamic Revolutionary Guard Corps approached and opened fire without issuing a distress signal or very high frequency challenge, the UKMTO said, leading to a surprise attack.

All crew members are safe, and the attack resulted in substantial damage to the ship's bridge, the report added. No fire or environmental damage has been reported.

"The situation continues to be volatile. Ships should take maximum caution and not take risks without security guarantees," a spokesperson for the International Maritime Organization said in a statement on Monday.