Two British volunteers providing humanitarian assistance in Ukraine have been captured by the Russian military, an aid organisation has said.

The non-profit Presidium Network said Paul Urey and Dylan Healey were detained at a checkpoint in southern Ukraine on Monday.

The Foreign Office is said to be urgently seeking more information.

Mr Urey's mother said she was extremely worried for his welfare, as he is Type 1 diabetic and needs insulin.

The two aid workers are believed to have been working independently, but were in touch with the Presidium Network.

They were said to be trying to rescue a family from a village south of the city of Zaporizhzhia at the time of their capture.

In a statement passed on by Presidium, Linda Urey said she was "extremely worried".

Presidium described Mr Urey as a family man who previously spent eight years as a civilian contractor in Afghanistan.

Mr Healey is described as a chef by training, who was driving the car at the time of their capture.

Presidium Network's founder, Dominik Byrne, told the BBC it had taken the men six hours of negotiation to get through the last Ukrainian checkpoint and into Russian territory, where they were detained.

Mr Byrne said he was making an appeal on behalf of the captured men "to get the support we need from the UK government and from the international community, as well as on the ground".

He said he also wanted "to get clarification about how they are and how safe they are" and to know whether they were being "treated properly".

On Thursday, the government confirmed that one Briton had been killed in Ukraine and another was missing.

Sources in Ukraine told the BBC the dead man is Scott Sibley, who is understood to have been fighting for Ukrainian forces.

Two other British men, Aiden Aslin, 28, and Shaun Pinner, 48, were captured earlier this month while fighting in the south-eastern city of Mariupol and shown on Russian state TV with apparent facial bruising.

In other developments:

Foreign Secretary Liz Truss said the UK is sending war crimes experts to help Ukraine investigate allegations of Russian atrocities, including experts in conflict-related sexual violence
About 8,000 British Army troops and dozens of tanks will take part in exercises across eastern Europe this summer. This is part of a long-planned action which was scaled up after the invasion of Ukraine, the Ministry of Defence said. (BBC)

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