The Ministry of Defence said the involvement of British troops in an anti-Taliban operation in Afghanistan was "in line" with their current advisory role:
In support of the Afghan forces who now have the security lead across the country, UK personnel do on occasion operate outside the usual UK area of operations in central Helmand in an advisory capacity.
These out-of-area operations have been a long-standing element of the UK mission in Afghanistan and are completely in line with our current role of providing training, advice and assistance to the Afghan National Security Forces.
There was no casualties among the British troops that returned to Helmand province for a secret mission, but a number of Afghan soldiers were killed, the Sunday Times said.
During the operation, a number of Taliban insurgents were detained and killed, more than 30 improvised explosive devices were found and destroyed and two vehicles were seized along with ammunition and weapons.
A major military operation in Afghanistan involving British troops was kept secret until after it was completed earlier this week.
The eight-day mission required the special permission of defence secretary Philip Hammond because of a government push to transfer combat operations to the Afghan National Army, The Sunday Times reported.
In recent months the British Armed Forces have been focusing on mentoring the ANA in preparation for their withdrawal from the country next year.