Investigators probing a blast on a Japanese supertanker near the Strait of Hormuz last week found remains of homemade explosives and have blamed the incident on a "terrorist attack", the UAE state news agency said on Friday.

The crew of the 333-metre-long M.Star reported an explosion shortly after midnight last Wednesday, injuring one seaman but causing no oil spill or disruption to shipping in the strategic waterway.

"An examination carried out by specialised teams had confirmed that the tanker had been the subject of a terrorist attack," the news agency WAM said, quoting an unidentified coastguard source.   

"UAE explosives experts who collected and examined samples found a dent on the starboard side above the water line and remains of home-made explosives on the hull", the source said.

The incident provoked several theories about the cause, ranging from a freak wave to a collision with a US nuclear submarine. Two days ago a militant group linked to Al Qaeda claimed responsibility for the incident.

Bordered by Iran, Oman and the United Arab Emirates, the narrow Strait of Hormuz handles 40 percent of the world's seaborne oil and is patrolled by US and other warships. Al Qaeda has threatened to attack shipping there in the past. - Reuters