A former British soldier jailed in Turkey for more than seven years after joining a Kurdish group fighting Islamic State has secretly fled the country and returned home.

Joe Robinson, 25, was on bail pending an appeal against his sentence on terrorism charges after he volunteered for the People’s Protection Units of Syrian Kurdistan (YPG), which Turkey considers a terrorist organisation.

He fled the country and returned to the UK without the permission of the Turkish courts, the BBC reported. He had begged the British government for help, saying he was emotionally drained by his ordeal.

Robinson was accused of fighting with the US-backed YPG in Syria, but he claims he was volunteering as a combat medic for the Kurdish group for a month in 2015.

He told the BBC he was getting his human rights back by fleeing Turkey, and that he had been obliged to take matters into his own hands. “I could not accept the sentence and charges as I am not a criminal,” he said.

Robinson, who is from Accrington in Lancashire, originally travelled to Syria in July 2015, telling his family he had gone to join the French Foreign Legion. After his month as a combat medic in Syria, he says he crossed the border into Iraq and joined the peshmerga, the government-backed army of Iraqi Kurdistan.

He returned to the UK in November 2015 and police arrested him at Manchester airport on suspicion of terrorism offences, but all charges were dropped after he spent 10 months on bail.

When he returned to the region last year, he was arrested on a Turkish beach. He and his fiancee, Mira Rojkan, were on holiday at the resort of Didim in south-west Turkey, when the authorities arrested and charged him with terrorism offences.

Joe Robinson with his partner, Mira Rojkan. Photograph: Mira Rojkan

Rojkan, 23, a Bulgarian national, was also arrested and given a suspended sentence for “terrorism propaganda” after apparently sharing Facebook posts with the Kurdish flag and links to Kurdish songs on YouTube.

Robinson was convicted in September and sentenced to seven and a half years in prison.

Turkey considers the YPG to be affiliated with the Kurdistan Workers’ party (PKK), which has been involved in an armed struggle against the state for decades. The YPG denies any affiliation, and is not a proscribed terrorist organisation in the UK.

Robinson, who toured Afghanistan with the Duke of Lancaster’s Regiment in 2012, spent four months in jail last year after his arrest in July. He was released on bail in November, but was not allowed to leave the country.

His family issued an appeal for his release last year. His mother, Sharon, said at the time: “He hasn’t done anything wrong. He’s committed no crime here, and none in Syria where he’s accused of committing a crime. So how is it wrong in a country he just went on holiday to?”

Ben Keith, a barrister specialising in extradition cases, said Robinson faced the risk of extradition back to Turkey but that he would have a human rights defence to challenge the case in court.

He added: “Turkey’s human rights situation is diabolical at the moment and so there are all sorts of problems with fair trial rights, and torture is systemic.”

The Foreign Office is not thought to have facilitated Robinson’s return to the UK. A spokesman said: “The FCO has previously confirmed the provision of consular support to Mr Robinson.”

Hundreds of foreign nationals, including Britons, have travelled to Syria in recent years to fight against Isis. Another former British soldier, James Matthews, 43, accused of attending terrorist training camps run by the YPG, had charges against him dropped in the UK in July after the crown concluded there was no longer a realistic prospect of a conviction.

Matthews, from east London, had pleaded not guilty to the charge of receiving instruction or training in Iraq and Syria on or before 15 February 2016 “for purposes connected to the commission of preparation of terrorism”.