An Afghan interpreter who says his work helped save the lives of many British soldiers and who claims he has been targeted by the Taliban has been refused asylum in the UK.

Aslam Yousaf Zai said he fled his home in Kabul after Taliban extremists singled him out for working with the British army and said they would kill him and harm his family.

He spent three years as a migrant travelling across Asia and Europe in poverty before he was smuggled into Britain in a refrigerated lorry a year ago and claimed asylum.

“I came here [because] I work with the British, they know my problem better than others,” Zai said. “Then I come here, for one year there has been nothing. Then after one year they give me interview at Home Office and in 16 days they refuse my asylum.”

The Home Office has accepted Zai worked with British troops but has said it does not believe he would be in danger in his home country and has told him to go back.

The letter outlining the reasons for his refusal said he had failed to demonstrate that the Taliban really knew that he was an interpreter for the British army.

Zai, 25, who learned English through private schooling, started working for the British army in 2009. He said he took up the job because he opposed the Taliban and hoped the international force would help his country.

His work took him far from home to Helmand, southern Afghanistan, where he patrolled with British forces trying to loosen the insurgency’s grip on the opium-growing territory. There, he said, he came under fire every day, his crucial job making him a particular target for insurgents.

“I was in the frontline, every day in patrol, every day in contact, ambush,” Zai told the Guardian. “We were talking with the locals asking people: ‘Where is the Taliban, what time are they coming to the village, what are they doing?’”

As well as acting as interpreter between local people and British soldiers, Zai also carried out intelligence work by listening in on Taliban radio communications.

“When you go in a patrol, they put IED or there is ambush, we hear their communication,” Zai said. “They say: ‘Now they are arriving.’ [We] translate [then say]: ‘Boss there is an IED, there is a contact.’ We stop the patrol. They [the Taliban] go: ‘There is the interpreter again.’”

But he said his close work with locals in Helmand led to his identification as a collaborator with the International Security Assistance Force (Isaf) when he returned to Kabul.

Zai said: “Every day we are sitting with people, we make shura [consultation]. And after that, when I come to Kabul, the people from there, they saw me in my village. And after that they passed the information for the Taliban. And the locals, my relatives, they know me in the village.

“Because interpreters, people don’t like them because they say they are spying for the British army, for the Americans, to kill the people, to search the compounds. And after that they are starting threats. My neighbours, the Taliban text my father’s phone, and during my job they threat[en] me in Icam [the radio system used by insurgents]. They say: ‘We know everything about you.’”

Zai said that after the threats began he quit his well-paid job with the British and did not leave his family home for three months. At least one of his friends was murdered after leaving a job interpreting for foreign soldiers, he said, and he feared that if he remained in Afghanistan he would suffer the same fate.

The Guardian has tried to contact current and former soldiers from the Royal Welsh regiment to corroborate Zai’s account. The Ministry of Defence said it would not ask serving soldiers to comment on a potentially political issue, while emails to a veterans’ forum went unanswered.

The Guardian also attempted to contact the Taliban to find out whether Zai appeared on their blacklists, but received no reply.

Sunder Katwala, director of British Future, said the British public had been consistently keen for Afghan translators, many of whom had taken significant risks to help British soldiers, to be offered security and protection. A YouGov poll in 2013 found that 60% of respondents backed the resettlement of Afghan interpreters in the UK if they faced risks.

“While I don’t know the details of his specific case, if Mr Zai does now have a well-founded fear of persecution by the Taliban as a result of his work for British forces, the natural instinct of most people in Britain will be that we do owe him a debt of honour,” Katwala said.

“I hope the Home Office will take steps to review this case, so as to ensure that any appeal that Mr Zai may make is treated properly and fairly. There has been extremely broad support, across the party political spectrum and from senior military figures too, for this country ensuring we do uphold our moral obligations to those who were willing to risk their lives to work with us in Afghanistan.”

Stephen Hale, chief executive of Refugee Action, said: “Britain needs an asylum system that protects and supports those fleeing persecution. Afghan interpreters put their lives on the line to work with British forces, as well as the lives of their families. We cannot abandon them.”

Hale said he hoped the decision would be overturned on appeal. “Around 40% of people are granted asylum when they apply and a further 25% of people are being granted on appeal,” he said. “So the Home Office is getting a quarter of their decisions wrong.”

When asked about Zai’s case, the Home Office said it had nothing to add to the reasons given in the initial refusal letter.