Taiwanese authorities launched a probe into Chen Shih-hsien in January after Seoul said it had detained a Hong Kong-registered ship suspected of transferring oil to a North Korean vessel.

Chen has now been charged with forgery for making a false declaration that a ship he had chartered was bound for Hong Kong when it actually sailed to international waters to sell oil, Kaohsiung district prosecutors said in a statement.

"Chen was well aware that the oil he purchased was being shipped to international waters for sale... and made four false declarations in 2017," the statement added.

Taiwan announced in September it was banning all trade activities with North Korea.

Local media have reported that Chen sold oil products through "a Chinese middleman".

However, Chen has insisted to reporters that he was "framed by China" and attempted suicide on January 19 after Taiwan's government announced a ban on all financial dealings with him and froze his companies' bank accounts due to the probe.

Sources have told AFP Chen claimed to prosecutors that he did not know the oil products were bound for a North Korean vessel.

He is currently on bail and has been barred from leaving Taiwan.

The case revolves around a ship called the Lighthouse Winmore, which was impounded in November by South Korean authorities after it allegedly transferred 600 tonnes of oil to the North's Sam Jong 2.

The vessel was chartered by the Billions Bunker Group which is incorporated in the Marshall Islands.

The group is actually run by Chen, according to the prosecutors' statement.

The US has previously asked the United Nations Security Council to blacklist 10 ships -- including the Lighthouse Winmore -- for violating sanctions against the North.