Iranian-backed forces are believed to have seized an oil tanker in the Gulf off the coast of the UAE, three maritime security sources said, after Britain’s maritime trade agency reported a “potential hijack” in the area on Tuesday.

Two of the sources identified the vessel as the Panama-flagged asphalt/bitumen tanker Asphalt Princess in an area in the Arabian Sea leading to the Strait of Hormuz, through which about a fifth of the world’s oil seaborne oil exports flow.

Iran’s foreign ministry had earlier said reports of security incidents involving several ships near the UAE coast on Tuesday were “suspicious”, and it warned of any effort to create a “false atmosphere” against the Islamic Republic.

Tensions have simmered in the region after an attack last week on an Israeli-managed tanker off the Omani coast killed two crew members and was blamed on Iran by the US, Israel and Britain. Iran denied responsibility.

The Bahrain-based US Navy’s Fifth Fleet and UAE authorities did not immediately reply to a Reuters request for comment about Tuesday’s incident.

The UK Maritime Trade Operations (UKMTO), in a warning notice based on a third party source, had earlier reported a “potential hijack” and advised ships to exercise extreme caution because of an incident around 60 nautical miles east of the UAE’s Fujairah emirate.

Britain’s Times newspaper also reported that the Asphalt Princess had been hijacked, citing British sources as saying they were “working on the assumption Iranian military or proxies boarded the vessel”.

On Tuesday afternoon at least five ships in the sea between the UAE and Iran updated their AIS tracking status to “Not Under Command”, according to Refinitiv ship tracking data. Such a status generally indicates a ship is unable to manoeuvre due to exceptional circumstances.

Reuters could not confirm this Refinitiv data had any connection to the reported incident.

The US and Britain said on Sunday they would work with their allies to respond to last week’s attack on the Mercer Street, a Liberian-flagged, Japanese-owned petroleum product tanker managed by

Israeli-owned Zodiac Maritime.

Iran denied involvement in that suspected drone attack and said on Monday it would respond promptly to any threat against its security.

Longtime adversaries Iran and Israel have exchanged accusations of carrying out attacks on each other’s vessels in recent months.

Tensions have risen in Gulf waters and between Iran and Israel since 2018, when then-President Donald Trump withdrew the US from Tehran’s 2015 nuclear deal with six world powers and reimposed sanctions that have crippled its economy.

US secretary of state Antony Blinken predicted a “collective response” to the Mercer Street incident.