A Singaporean shipbroker and its Indian managing director have become the latest in the shipping industry caught up in the US "maximum pressure" campaign against Iran.

Included in a swathe of blacklistings for allegedly helping Iran to sell millions in petrochemicals were Murtuza Mustafamunir Basrai and his company Strait Shipbrokers.

It was not immediately clear what either did to incur the sanctions, as neither Ofac nor the US State Department immediately offered details and Strait did not return a request for comment.