MYTILENE — The trial of 24 aid workers and volunteers who participated in migrant rescue operations resumed Friday on an eastern Greek island, a prosecution that has drawn widespread criticism from international human rights groups.

The Greek and foreign defendants argue they were doing nothing more than assisting people whose lives were at risk. Their lawyers have objected to the procedures followed by the prosecution, which could lead to the court on the island of Lesbos ordering prosecutors to refile the case.

Those on trial include prominent Syrian human rights worker Sarah Mardini, a refugee and competitive swimmer whose sister Yusra Mardini was part of the refugee swimming team at the Olympic Games in 2016 and 2021. The sisters’ story was made into a Netflix movie.

Mardini, who was not present for Friday’s hearing, and fellow volunteer Sean Binder, who was in Lesbos to attend the trial, spent more than three months in jail in Lesbos after their 2018 arrest on misdemeanor charges that included espionage, forgery and unlawful use of radio frequencies.

The two are also under investigation for felony offenses, but prosecutors have not brought any of the more serious charges against them. The case was initially set to proceed in 2021 but was postponed over procedural issues.

“Targeting human rights defenders and individuals engaged in acts of solidarity is both incompatible with states’ international obligations and has a chilling effect on human rights work,” Council of Europe Commissioner for Human Rights Dunja Mijatovic said in a statement Thursday.

She mentioned the trial on Lesbos, as well as other prosecutions of human rights workers, smear campaigns, cumbersome registration procedures for non-governmental organizations and pressure on journalists as having “undermined the protection of human rights and shrunk the civic space” in Greece.

“I urge the Greek authorities to ensure that human rights defenders and journalists can work safely and freely, by providing an enabling environment for their work and publicly recognizing their important role in a democratic society,” Mijatovic said.

Harlem Desir, the senior vice president for the International Rescue Committee’s Europe section, called on the European Union to “forge a new approach” when dealing with asylum-seekers who attempt to enter EU countries by crossing the Mediterranean Sea.

The trial, he said, was “emblematic of a broader trend towards the EU disrupting people’s journeys and deterring people from reaching Europe, often leaving them trapped in dire conditions or at risk at sea, rather than protecting them along their journeys or providing routes to safety.”

Greece, which saw around a million people cross to its shores from neighboring Turkey at the height of a refugee crisis in 2015, has clamped down on migration, erecting a fence along much of its land border with Turkey and increasing sea patrols near its islands.

Greek officials say they have a strict but fair migration policy. They also deny, despite increasing evidence to the contrary, conducting illegal summary deportations of people arriving on Greek territory without allowing them to apply for asylum, a procedure known as “pushbacks.”