Manchester City are insisting on a buy-back clause in their sale of Angus Gunn to Southampton.

The Daily Mail says Gunn is set to complete a move to Southampton for an initial £10million.

City could pocket up to £13.5m should additional clauses be triggered.

It is understood City have inserted a buy-back option in the deal in case they want to re-sign Gunn in the coming years.

Gunn spent last season on loan at Norwich City in the Championship and received his first England call-up last November.