Iran’s Revolutionary Guard naval forces seized a foreign oil tanker in the Strait of Hormuz over alleged fuel smuggling, state-run media reported Friday.

The vessel was carrying approximately 4 million litres of fuel when it was intercepted, according to Mojtaba Ghahramani, a provincial justice department official quoted by IRNA news agency.

Authorities detained 16 foreign crew members but did not reveal their nationalities or the tanker’s flag.

Iran periodically detains vessels in the strategic waterway on smuggling allegations. In November, Iranian forces seized another ship transiting the strait, citing violations including illegal cargo.

A fifth of globally traded oil and a quarter of seaborne oil passes through the narrow Strait of Hormuz.

Tehran has repeatedly warned it could block the waterway, whilst the US Navy’s 5th Fleet, based in Bahrain, maintains a presence to ensure shipping lanes remain open.

Tensions between Iran and the West have escalated in recent years. Washington accused Tehran of carrying out limpet mine attacks that damaged tankers in 2019, and a 2021 drone strike on an Israeli-linked vessel that killed two European crew members.

The incidents followed Washington’s withdrawal from Iran’s 2015 nuclear agreement during US President Donald Trump’s first presidency.

Tehran seized the UK-flagged Stena Impero tanker in the Strait of Hormuz in July 2019, holding the vessel and its 23 crew members for more than two months in what was widely seen as retaliation for Britain’s detention of an Iranian tanker off Gibraltar weeks earlier.

Iran also detained the Portuguese-flagged MSC Aries in April 2024.

Relations with Tehran deteriorated further this year, culminating in a 12-day conflict between Iran and Israel in June that saw Israeli strikes against Iranian nuclear facilities and top military commanders and nuclear scientists, while Iran’s retaliatory missile attack caused 28 deaths in Israel.