Yemen's Houthis attacked al-Dhabba oil terminal in Hadhramaut province on Monday, the group and Yemen's internationally recognized government said.
The Iran-aligned Houthis fired a projectile from a drone that landed at the entrance of the terminal, which is located in the town of al-Shihr, two workers at the terminal told Reuters.
Panamanian-flagged vessel Pratika had entered the terminal to load a shipment of crude but left after the attack, the workers said.
The Maritime Trade Operations (UKMTO), which is part of the British Royal Navy, said it received a report that a missile or rocket attack had been carried out at al-Shihr against a single-point mooring at 1212 GMT. All crew and the vessel were safe, UKMTO said, withholding the ship's name.
The Houthis' military spokesman said a ship was forced to leave the port at al-Dhabba.
Refinitiv data showed Pratika in the Gulf of Aden at 1952 GMT, headed for Suez.
The Saudi-backed government's military said al-Dhabba's oil export platform was hit.
The seven-year-old war between the Iran-aligned Houthis and a military coalition led by Saudi Arabia has divided Yemen, with the movement largely holding the north.
The Houthis have been attacking oil ports in government-held areas as they pile pressure to extract economic gains in U.N.-led talks for an extended truce deal that have dragged on. Officials say these attacks have disrupted crude oil exports, choking state revenues.
(Reuters - Reporting by Mohammed Alghobari and Reyam Mokhashef; Additional reporting by Nayera Abdallah in Cairo; Writing by Yousef Saba in Dubai, Editing by William Maclean)