LONDON: Attacks on tankers sailing through the Strait of Hormuz hit their highest last week of any week since the Iran war began, according to maritime security sources tracking incidents.

Attacks, attempted attacks and harassment activity including drone overflights, surveillance and hailing using VHF radio by Iran's Revolutionary Guards have persisted in the strait, the US Navy-led Joint Maritime Information Center (JMIC) said in a note on Sunday.

"These actions continue to demonstrate Iran’s intent to assert presence along key transit lanes and maintain pressure on transiting vessels," the JMIC said.

In the week of Sept. 28 through Oct. 5, there had been at least 12 attacks on oil, liquefied natural gas and liquefied petroleum gas tankers around the Strait of Hormuz, according to data from three maritime security sources who analysed incidents based on information received from the area.

That was the highest number of attacks in a single week since the US war with Iran began on February 28, the sources said.

Separate data collated by the UN's shipping agency, the International Maritime Organization (IMO), showed nine incidents involving vessels in the same week.

The UN body tends to take longer to verify and officially record incidents, maritime sources say.

The closest week in terms of comparable incidents was the week of July 13 when there were eight incidents, separate IMO data showed.

Gulf oil exporters topped pre-war levels for about half of September, shipping data showed on Monday, though attacks on tankers and logistical constraints cloud the outlook for sustained higher flows.

India's foreign ministry said on Tuesday that 12 crew members were injured after an unknown projectile struck Panama-flagged oil tanker On Peace while it was passing through the Strait of Hormuz.