Maersk Tankers would honour customer agreements entered into before May 8, but then wind them down by November 4, "as required by the re-imposed US sanctions," the company told AFP.

A former subsidiary of the Danish maritime group AP Moller-Maersk, Maersk Tankers was in October 2017 sold for $1.17 billion to APMH Invest, a subsidiary of the investment A.P. Moller Holding.

The nuclear deal, reached in July 2015 between Iran and Germany, China, the US, France, Britain and Russia, called for Tehran to freeze its nuclear programme in exchange for getting some international sanctions against the Islamic Republic lifted.

Washington announced in early May that it would withdraw from the agreement and reimpose sanctions against Tehran.

Iran's oil exports amounted to one million barrels a day, mostly to Asia and some European countries, before sanctions were lifted. They have since climbed to 2.5 million barrels.