Kalidou Koulibaly
Kalidou Koulibaly in action for the French Under-20 side. [Reuters]

Manchester United manager David Moyes will look to strengthen his struggling defence during the January transfer window by attempting to sign French defenders Kalidou Koulibaly and Kurt Zouma.

It has been a difficult start for Moyes who has overseen the club's worst start to a season for some 24 years. United find themselves in 12th place after six Premier League games, having lost their last two to Manchester City and West Brom.

The reigning champions have looked susceptible at the back, conceding eight goals in just six league games, and Moyes may well attempt to address this situation once the transfer opens in the New Year.

The Daily Mail reports that Moyes is monitoring the progress of Koulibaly who has impressed for Belgian side Genk this season with a string of commanding displays.

A powerful central defender who stands at a towering 6ft 5", he only joined Genk from Metz in the summer of 2012 but has already made a significant impression and has particularly stood out while playing in the Europa League.

Koulibaly made 11 appearances for France at Under-20 level but has yet to receive a first cap at senior level.

The 22 year old is said to have also attracted interest from Manchester City who are also interested in another United target in St. Etienne defender Zouma.

A similarly powerful defender, Zouma is just 18 years old but has already attracted interest from several major European clubs after impressing with the Liguie 1 side.

City's top scout Gary Wirthington watched the defender in action for the French Under-21 side last week but it is believed that Manchester United are also keen to prise him away from St. Etienne.

Moyes has a number of options in defence with Rio Ferdinand, Nemanja Vidic, Chris Smalling, Phil Jones and Jonny Evans all competing for a starting berth but it seems the former Everton boss feels he needs a more commanding presence.

Having come under pressure for failing to significantly strengthen the squad over the summer, Moyes will be desperate to address this situation in January and the two French defenders may well be the subject of bids.