Britain said on Monday it had detected a first human case of flu strain A(H1N2)v, which is similar to a virus currently circulating in pigs, and that the individual concerned had experienced a mild illness and fully recovered.

The UK Health Security Agency (UKHSA) said that the case was detected as part of routine national flu surveillance and the source of infection was not known.

"This is the first time we have detected this virus in humans in the UK, though it is very similar to viruses that have been detected in pigs," UKHSA incident director Meera Chand said.

Close contacts of the case are being followed up by the authorities, the statement said, adding that the situation was being monitored with increased surveillance in surgeries and hospitals in North Yorkshire, a region of northern England.

In 2009, the swine flu pandemic in humans infected millions of people. It was caused by a virus which contained genetic material from viruses that were circulating in pigs, birds and humans.

The UKHSA said that based on early information the infection detected recently in Britain was different from the 50 or so other human cases of the strain found elsewhere globally since 2005.