Denmark's shipping and container giant Maersk said on Sunday it was halting passage through the narrow Strait of Hormuz in the Gulf, next to Iran, citing "safety" reasons.

"We are suspending all vessel crossings in the Strait of Hormuz until further notice," the Danish group said in an online advisory.

"The safety of our crews, vessels and customers' cargo remains our key priority," it said.

It made the announcement after Iran's Revolutionary Guards declared the strait closed.

State media in Oman, which sits on the other side of the strait, said Sunday an oil tanker off its coast was targeted and four of its crew were hurt.

And the United Kingdom Maritime Trade Operations (UKMTO) Centre said Sunday that another ship, one off the United Arab Emirates's (UAE) coast, also near the Strait of Hormuz, reported being hit "by an unknown projectile causing a fire."

MSC, another big shipping company, told its vessels in the Gulf "to proceed to designated safe shelter areas until further notice."

The Strait of Hormuz is a strategic waterway through which passes nearly a quarter of the world's seaborne oil supplies, and a significant amount of cargo to and from Gulf ports.