Two British humanitarian workers in Ukraine have been detained by Russian soldiers on suspicion of being “spies,” according to a non-profit organization and the family of one of them.

According to Presidium Network, a humanitarian organization, Russian soldiers “caught” Paul Urey and Dylan Healy on Monday at a checkpoint south of the city of Zaporizhzhia in northeastern Ukraine.

The two were arrested while driving to help a widow and her two children in Zaporizhzhia. They were claimed to be operating separately to try to get vulnerable Ukrainians out.

Presidium Network said it had offered to help Urey and Healy after hearing of their volunteer efforts, but the pair were not affiliated with the non-governmental organisation, which has been active in Ukraine.

After the checkpoint arrests, the woman’s house “was stormed by armed Russian soldiers”, Presidium co-founder Dominik Byrne said in a statement.

“They made her husband lie on the floor and asked her how she knew these British spies,” he said, insisting that the pair were not spies but humanitarian workers.

Urey, born in 1977, is a Type 1 diabetic and needs regular insulin doses, according to his mother Linda Urey, who said his family was “extremely worried”.

“He was out there on his own accord. We want everyone’s support to bring (my) son home and pray he is safe,” she said.

A family man with children, Urey is a well-travelled humanitarian who worked for eight years in Afghanistan, according to Presidium.

It said that Healy, born in 2000, is a kitchen manager for a hotel chain in Britain.

The NGO confirmed it was working with Britain’s foreign ministry, which has been urgently seeking further information on the case.

The news comes a day after the ministry said one UK citizen had been killed in Ukraine and another was missing, with both reportedly involved in fighting against Russian forces.

Former allies paid tribute to the slain man, who was identified as a military veteran named Scott  , according to British media.

His death, just over two months after Russia launched its invasion and Ukraine pleaded for international troops to help, is thought to be the first of a British soldier engaged in the conflict.