Japanese trade minister Hiroshige Seko said Thursday that two tankers carrying "Japan-related" cargo were attacked near the Strait of Hormuz.
Hiroshige Seko said on Thursday that all crew members were safely rescued. He said the government has set up a task force and that the government has informed the shipping industry to use precautions.
The Japan Shipowners' Association said one of the two ships attacked is a Panamanian-registered chemical tanker belonging to its Japanese member and was on its way to Singapore and Thailand, not to Japan.
It said all 21 Filipino crew members were uninjured.
The attacks came as Japanese Prime Minister Shinzo Abe was wrapping up a two-day trip to Iran with a mission to ease tensions between Tehran and Washington. The timing of the attack was especially sensitive while Abe's high-stakes diplomacy mission was underway.
On Wednesday, after talks with Iranian President Hassan Rouhani, Abe warned that any "accidental conflict" that could be sparked amid the heightened U.S.-Iran tensions must be avoided.
No one has claimed responsibility or explained how the tankers were attacked.
Benchmark Brent crude spiked at one point by as much 4% in trading following the attack, to over $62 a barrel, highlighting how crucial the area remains to global energy supplies. A third of all oil traded by sea passes through the strait, which is the narrow mouth of the Persian Gulf.
The latest incident in the region comes after the U.S. alleged that Iran used mines to attack four oil tankers off the nearby Emirati port of Fujairah last month. Iran has denied being involved, but it comes as Iranian-backed rebels in Yemen also have launched missile and drone attacks on Saudi Arabia.
