At least 30 commercial ships dropped anchor on Wednesday around Gabon’s waters after military officers said they had seized power in the Central African country, according to data and maritime sources.

Military officers in the oil-producing country said they had put President Ali Bongo under house arrest, after the country’s election body announced that he had won a third term. Borders were closed and state institutions were dissolved.

There was already a build-up of vessels backed up on Wednesday.

The vessels included commercial cargo ships as well as tankers that had stopped near to the country’s major ports including Owendo, near to the capital Libreville, and Port Gentil further south, ship tracking data from analytics company MarineTraffic showed on Wednesday.

British maritime security company Ambrey said port operations in Libreville had stopped and no vessels had entered or departed the port since the announcement of the coup.

“Ambrey is aware that movements in and out of Gabon have been closed down following an early morning announcement by military officials,” it added in an advisory.

Germancontainer shipping group Hapag Lloyd HLAG.DE has one of its vessels currently in Libreville and the ship is unable to sail due to the border closures, a company spokesperson said on Wednesday.

Ship tracking data showed a separate container vessel operated by Denmark’s A.P. Moller-Maersk MAERSKb.CO also moored in Libreville. Maersk did not immediately respond to a request for comment.

Assala Energy, which is wholly owned by Carlyle Group CG.O, said its oil production in Gabon had been unaffected.

Ambrey added that despite disruption in Gabonese ports, offshore terminals remained operational.

Danish shipping group NORDEN DNORD.CO, which operates port logistics in the country for a project with manganese mining company Comilog, said that its main priority was to ensure the safety of employees and its operations in Gabon. Comilog is a subsidiary of French metallurgical group Eramet >.

Source: Reuters reported by Jonathan Saul and edited by Alex Richardson and Conor Humphries