The crew of a crude tanker seized three months ago in Equatorial Guinea have appeared in court in Port Harcourt and charged with offences linked to the illicit oil trade and piracy after the ship was forced to sail to Nigeria.

Sixteen of the 26-strong crew appeared in court in the port city on Monday before being bailed and taken back to the 300,000-dwt Heroic Idun (built 2020) which is anchored at the Bonny offshore terminal, according to shipping movement data. The other 10 are expected in court on Tuesday.

The first 16 all pleaded not guilty to charges including an attempt to lift oil without a licence and one offence under Nigeria’s suppression of piracy act, said Stephen Askins, a maritime lawyer who has been working with insurers, owners, ship manager OSM and unions to try to free the men.

“The fact they have been charged shows that the state is ready to go to trial,” he said.

The charges date from an incident in early August when the crew mistakenly identified a Nigerian naval vessel as a potential pirate craft and left the Akpo oil terminal at Bonny where it had been waiting to load oil.

The Ray Car Carriers-owned VLCC was eventually arrested by a vessel from the Equatorial Guinea navy. The Heroic Idun was held on the island of Bioko for nearly three months before it was handed over to the Nigerian navy for further investigations into crude oil theft.

The crew were ordered on board the VLCC — including the chief engineer who had been in hospital with chest burns — and on Friday sailed the ship back to Bonny.

The charges against the men are in line with a statement by the Nigerian navy last week that said the crew could be charged with unauthorised entry of a restricted zone around an oilfield, illegally attempting to load crude and falsely accusing a Nigerian navy ship of piracy.

Nigeria said that the VLCC’s crew should have known that it was being approached by one of its vessels. “If the vessel is found innocent, it will be released. If found guilty of breaking the laws of Nigeria, the appropriate sanctions will be enforced, to send a strong message of deterrence,” said the navy on Wednesday.

Lawyers for the VLCC unsuccessfully applied to the courts to stop the ship and the crew being moved, claiming it was an unlawful act of rendition by Nigeria.

They fear the government will seek to use the men as an example of how they are cracking down on rampant oil theft with presidential elections due to be held next year.

Charges were laid against the crew on 7 November, the day after Equatorial Guinea’s vice-president announced the tanker would be handed over to Nigeria.

The ship’s owners and insurers have appealed to the International Maritime Organization to act in the case. Labour organisations have also demanded that the crew are returned home.

“We have at hand a humanitarian crisis on board where the entire crew is stressed, fatigued and requires urgent relief,” said the National Union of Seafarers of India.