Two of the vessels, belonging to state-owned shipping giant Cosco, passed through the strait while exiting the Gulf on Monday morning, data from the MarineTraffic monitor showed.

A third ship, a Hong Kong-flagged oil and chemical tanker called the Egret, crossed earlier on March 25 sailing from east to west, according to maritime analytics firm Kpler.

"Following coordination with relevant parties, three Chinese vessels recently transited the Strait of Hormuz," foreign ministry spokeswoman Mao Ning told a press conference.

"We express our gratitude to the relevant parties for the assistance provided," she said.

She did not mention Iran or specify who was involved in coordination efforts.

Shipping through the strait has slowed to a trickle since Iran effectively blocked access following US-Israeli attacks on the country.

The two Cosco vessels -- the CSCL Indian Ocean and the CSCL Arctic Ocean -- are both ultra-large container carriers.

They passed close to Iran's Larak Island and are bound for Port Klang in Malaysia.

The ships had aborted an attempt to transit on Friday, according to MarineTraffic.

Cosco declined to comment on the transits when contacted by AFP.

Iran has said the Strait of Hormuz is open to ships of "friendly countries". It maintains healthy diplomatic ties with China.

Cosco said on Wednesday it was resuming bookings for shipments from Asia to several Gulf countries, though without using routes that transit Hormuz.

The Shanghai-based firm had suspended bookings for services through the strait earlier in March due to the war.