LONDON, Aug 19 (Reuters) - Britain is unable to evacuate unaccompanied children from Afghanistan, Defence Secretary Ben Wallace said on Thursday when asked about footage which showed a young child being handed over a wall to Western soldiers at Kabul airport. The footage, which Reuters was unable to immediately verify, showed a small girl being handed over a wall to British and U.S. soldiers at Kabul airport. Wallace said the child was passed over the wall as her family was being taken out. "We can"t just take a minor on their own," Wallace told Sky News when asked about the footage. "You will find as you see in the footage I think you"re showing now, the child was taken - that will be because the family will be taken as well." "It will be the challenge trying to make it through that crowd," Wallace said. "We are finding other ways of dealing with that but that is what"s happening." Wallace said British soldiers at the airport were facing a difficult situation given the desperation of some Afghans to leave. "It is very very difficult for those soldiers as you"ve seen in your own footage, dealing with some desperate, desperate people, many of whom are just wanting to leave the country," Wallace said. Reporting by Sarah Young and Guy Faulconbridge; Editing by Kate Holton Our Standards: The Thomson Reuters Trust Principles.