Moscow on Friday released a video of a British national said to have surrendered to Russian forces in Mykolaiv, southern Ukraine.
In a video message, Andrew Hill said he came to Ukraine from the Polish city of Rzeszow with a group of seven people because he wanted to "help Ukraine."
According to him, once the group crossed the border, he was first helping refugees, but then was asked to "help more," and he was handed a CZ assault rifle and transported by bus to the Mykolayiv region, located in a peninsula in Ukraine's steppe region, 65 kilometers (40 miles) from the Black Sea.
He claimed he was promised payment but was never paid.
Asked if he had anything to say to other British citizens, he responded: "They really need to think about it (going to Ukraine) because this doesn't involve us."
Hill said he was from Plymouth, England and that he has four children and a partner.
On his bandaged arm, he said he was injured in a battle and that Russian forces gave him medical treatment.
According to UN estimates, at least 2,829 civilians have been killed and 3,180 injured in Ukraine since Russia launched a war on Ukraine on Feb. 24, with the actual figure feared to be much higher.
According to the UN refugee agency, more than 8.3 million Ukrainians have fled to neighboring countries.