US National Security Adviser John Bolton said at a press roundtable in Tokyo ahead of a four-day state visit to Japan by US President Donald Trump that recent attacks on oil tankers and pumping stations were a "manifestation of concerns" about Iran.

Axar.az reports citing foreign media that Bolton claimed that Washington has "deep and serious" intelligence on the threat posed by Iran but declined to provide any details.

On 12 May, four oil tankers, including two Saudi vessels and a UAE-flagged ship, were targeted by a mysterious attack near the UAE’s exclusive economic zone. Although no one has claimed responsibility for the sabotage, US Secretary of State Mike Pompeo claimed on Tuesday that it was "quite possible" that Tehran was behind it.

The attack comes as tensions have further escalated between the United States and sanctions-battered Iran after the former boosted military presence in the Gulf region earlier in May, deploying a bomber task force and an aircraft carrier to the region.