A container ship sank in the Strait of Hormuz on Wednesday as Iran escalated its attacks on commercial vessels.

The GFS Pride, registered in Singapore, sank after it was struck by an unidentified projectile and caught fire. The ship's 21 crew members were safely evacuated and no injuries were reported, according to the Maritime and Port Authority of Singapore.

"Such attacks are unprovoked, unjustifiable and a breach of international law," the Singapore maritime authority said in a statement Wednesday.

Iran's Revolutionary Guard claimed early Wednesday that a container ship exploded and sank after hitting a naval mine, according to the state news agency Tasnim. But there is no independent evidence to confirm that a mine is what caused the Pride to sink, according to the maritime security firm Marisks.

Iran's claims are "consistent with an ongoing psychological operations campaign aimed at generating fear, increasing uncertainty and discouraging commercial shipping" in Hormuz, Marisks said in a security alert.

Iran has escalated its strikes on commercial ships transiting Hormuz in recent weeks, as it tries to choke off a rebound in crude oil exports through the strait.

More than 20 vessels, mostly oil tankers, have come under attack this month in Hormuz, the Persian Gulf and Gulf of Oman, according to incident reports from the United Kingdom Maritime Trade Operations Centre.

The attacks this month have left two sailors missing and 12 injured, according to the International Maritime Organization, a United Nations' agency.

Crude oil exports through Hormuz hit prewar levels in September as the U.S. military guided tankers through the strait, but shipments have since pulled back as attacks have increased.

Crude exports through Hormuz averaged 8.5 million barrels per day (bpd) in the week ended Oct. 12, nearly 40% below normal levels before the Iran war, according to data from Kpler.

Shipments from the entire region, including pipelines to the Gulf of Oman and Red Sea, stood at 14 million bpd, or nearly 20% below prewar levels, the data showed.

Daily flows are volatile, with only 3 million barrels of crude transiting Hormuz on Monday while 6 million barrels passed through the strait on Friday, according to Kpler.