An armed group linked to al-Qaeda has claimed responsibility for last week's attack on a Japanese oil tanker near the Strait of Hormuz.
The Brigades of Abdullah Azzam, in a statement, said it carried out the attack "to weaken the infidel global order which is thrust unto Muslim lands and which loots its resources".
"Last Wednesday, after midnight, the martyrdom-seeking hero Ayyub al-Taishan ... blew himself up in the Japanese tanker M Star in the Strait of Hormuz between the United Arab Emirates and Oman," the statement said.
The group said the attack was carried out in the name of Omar Abdul Rahman, the Egyptian "Blind Sheikh" imprisoned in the United States for his role in the 1993 World Trade Center bombing in New York.
"We delayed the publication of the statement until our heroes returned safely to their bases."
No independent verification of the statement was immediately available.
Owners of the M Star had previously said the tanker appeared to have been hit by an explosion on July 28 in the waterway between Iran and Oman.
Officials had said crew members saw a flash and heard an explosion in the incident shortly after midnight local time a week ago.
One crewman was slightly injured in the explosion, which caused minor damage to the ship.
The Japan-bound vessel, crewed by 16 Filipinos and 15 Indians, was carrying 270,000 tonnes of crude oil but did not suffer a spill.
The ship arrived under its own steam in the United Arab Emirates for repairs, and an investigation into the incident was launched.
The Strait of Hormuz, less than 100km wide at its widest point, separates Oman from Iran and is the gateway into the oil-rich Gulf.
Japan, the world's second biggest economy, sources some 90 per cent of its oil from the Middle East, much of it from the Gulf.