Global shipping giant MSC announced Monday it was formally halting certain export shipments from the Gulf because of the Middle East war and that "all affected cargo will be discharged".

"In light of the ongoing and exceptional security situation in the Middle East... it is necessary to declare an 'End of Voyage' for certain export shipments" from Gulf ports, "whether located ashore or already onboard", MSC said in an advisory notice to customers.

The announcement from the world's biggest container shipping firm came as the Iran war sent oil prices soaring on Monday after Tehran, under a new supreme leader, fired a fresh barrage of missiles at its Gulf neighbours and signalled that the strategic Strait of Hormuz would likely remain shut.

The strait is the only sea passage from the Gulf towards the Indian Ocean, through which nearly a quarter of the world's seaborne oil supplies pass, as well as a significant amount of cargo.

MSC said its decision "reflects the exceptional nature of the current circumstances" and "does not constitute a breach of contract".

"All affected cargo will be discharged and made available to cargo interests at the designated port. From that point onwards, custody, risk, and responsibility for the cargo will transfer to the cargo interests," it said.

After discharge -- the unloading of cargo from a ship, when responsibility for it is transferred back to the client or recipient -- customers who want to continue the transport of their shipments with MSC via alternative routes or solutions can do so under a new contract of carriage, the shipping firm said.

MSC said it would try to help customers identify and organise the most appropriate onward route, for which a mandatory surcharge of $800 per container will apply, to cover associated additional operational and logistical costs.

"Customers are kindly requested to contact their local MSC office for details of the designated port and to confirm recovery or onward transport instructions," it said.

"MSC sincerely regrets the necessity of this decision, which arises from exceptional circumstances beyond its control."

The United States and Israel began their strikes on Iran on February 28. Since then, Iran has launched missile and drone attacks on targets in several Gulf countries.

On March 1, MSC said it had told its vessels in the Gulf to head to safe shelter and had suspended all bookings for worldwide cargo to the Middle East.

Then on March 3, the Geneva-based company said all shipments destined for ports in the Gulf were being diverted to the nearest safe port for discharge.

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