A group of aid workers who were put on trial in Greece for people smuggling after rescuing migrants in the Mediterranean island have been acquitted of all charges.

The 24 former volunteers included former Syrian migrant and competitive swimmer Sara Mardini, who returned to the island of Lesbos to rescue other refugees, and whose heroic story was told in the Netflix drama, ‘The Swimmers’.

The group were arrested seven years ago, accused of human trafficking and other offences – and could have faced up to 20 years in jail.

They had worked for an NGO that rescued asylum-seekers at risk of drowning between 2015 to 2018, when hundreds of thousands of migrants crossed the narrow straits from Turkey to Greece.

Their case was widely condemned by aid agencies and human rights advocates as an attempt to criminalise humanitarian aid.

The defendants all worked for the Emergency Response Centre International (ERCI).

They were arrested in 2018. Some other accusations of spying were dropped but their trial on the remaining charges of facilitating the illegal entry of foreigners into Greece, money-laundering and membership of a criminal organisation began last month.

“All defendants are acquitted of the charges” because their aim was “not to commit criminal acts but to provide humanitarian aid”, Judge Vassilis Papathanassiou told the court.

Prosecutors had earlier recommended their acquittal, saying “no independent basis establishing the criminal liability of the defendants has been demonstrated”.

During the trial, the court heard evidence from a senior police officer testifying about the defendants’ use of an encrypted messaging service, WhatsApp, to share information about the location and state of boats carrying migrants.

The judge ruled that “a communication group on the internet cannot be regarded as a criminal organisation,” saying: “Waiting to rescue a human life cannot be considered facilitation of illegal entry.

“None of the defendants attempted to act in such a way as to allow any of the transported persons – refugees or otherwise – to evade inspection by the authorities,” he said.

Ms Mardini’s lawyer said he was “astonished” that it took 2,889 days for the prosecution to realise the accusations made no sense.

Ms Mardini and her sister Yusra were Syrian swimming champions who famously helped to save fellow refugees on a sinking raft in the Aegean Sea.

The incident became the subject of a Netflix movie called ‘The Swimmers’, which told the story of the sisters, who escaped their war-torn homeland to find a new lives in Europe.

It describes how they were packed into an overloaded four-metre inflatable dinghy when they set off to reach Europe in August 2015.

Fifteen minutes into their journey toward the Greek island of Lesbos – just ten kilometres away – the dinghy’s engine died in rough seas and its occupants were tossed around helplessly by high waves.

As it seemed the craft would sink, the passengers began to pray.

But Yusra and Sara, who had both swum internationally for Syria, jumped into the water to try and stop the boat capsizing, clinging on to try and keep the flimsy dinghy headed in the right direction.

The sisters swallowed sea water while being buffeted by waves, their eyes stinging and muscles straining while passengers – including families with small children – frantically used their mobile phones to try to call for help.

They eventually made contact with the Greek coastguard who simply told them to turn back, but they could not reach the Turkish coastguard.

The Mardini sisters clung on for three hours, their muscles aching from the cold and their skin chafing from their life jackets.

Suddenly, the engine was restarted and the sisters, who had been in the water longest while the male passengers took turns to help them, climbed back in the boat.

A statement from Amnesty International said: “We hope today’s decision sends a strong signal to Greece and other European countries that solidarity, compassion and defending human rights should be protected and celebrated, not punished.”