The Greek trial of 24 aid workers accused of people trafficking, spying and membership of a criminal organisation has has been postponed because the court does not consider itself competent to deal with the case.

It is not clear if a higher tribunal will take over the case or when the trial will take place.

Retired Duch banker and aid worker Pieter Wittenberg, who had travelled to Lesbos to be present at his trial, said he was very disappointed at the delay. ‘We had wanted to put an end to the whole thing and make clear once and for all that humanitarian help can never be a crime,’ he told NPO Radio 1.

Wittenberg and most of the other aid workers all worked for the Greek aid organisation Emergency Response International (ERCI).

Wittenberg, an experienced sailor, guided in refugees off the coast of Lesbos every night, using the organisation’s boat. ‘We would see boats but did not take refugees on board. We remained at a distance, gave them life jackets and said: follow us. We’ll take you to a spot where it is safe to land,’ Wittenberg said.

One of Wittenberg’s fellow defendants, 27-year-old Irish law student Sean Binder told the Guardian after a chaotic hearing on Thursday, from which the media were banned, that he was ‘very angry and disappointed. ‘This just means months of more limbo as we wait for justice. I may not have been found guilty today but effectively I’m still not free. The criminalisation of humanitarianism continues.’

Lawyers for the group have criticised the Greek legal proceedings, saying that it is unclear what the charges against each of the group members are and that documents have not been translated for the non-Greek members of the group.

‘Unfortunately the court did not find itself competent to rectify these mistakes either,’  Wittenberg’s lawyer Maria Spiliotakara said.