West Ham United are reportedly keeping tabs on Manchester United's transfer activity with a view to making a move for Chris Smalling this summer.

United are understood to have made signing a centre-back their priority during the current window and have been linked with a big-money bid for Tottenham Hotspur's Toby Alderweireld.

Should the Red Devils bring in an extra defensive option then it would leave Jose Mourinho with six centre-backs on his books, and Metro reports that West Ham are hoping Smalling may be considered surplus to requirements.

Mourinho is not thought to be actively looking to offload any of his central defenders, but the Hammers could use the competition for places to prise Smalling away from Old Trafford.

West Ham boss Manuel Pellegrini and new director of football Mario Husillos have begun to outline their transfer targets, with defence a priority for them.

Swansea City duo Alfie Mawson and Lukasz Fabianski have been touted as possible targets for the capital outfit, although a long-term injury to Manuel Lanzini - who could miss the majority of next season - may force them to rethink their transfer plans.