By Coral Barry and Wayne Veysey

Mauricio Pochettino has sanctioned Tottenham to make defensive reinforcements in the summer transfer window, Football Insider sources understand.

Spurs are targeting new defenders despite having the meanest back line in the Premier League this season.

The London club’s title challenge has been built upon a defence that has conceded just 25 goals in 34 league matches, comfortably the best record in the division.

Toby Alderweireld has been named in the PFA Premier League team of the season after forming an outstanding centre-back partnership with fellow Belgian Jan Vertonghen.

Either side of them, Danny Rose and Kyle Walker have had fine seasons in the full-back positions, while defensive understudies Kevin Wimmer, Ben Davies and Kieran Trippier have all stood in impressively at various times.

But Spurs want more defensive options as they prepare for a return to the Champions League next season.

Following Eric Dier’s transformation this season into a midfield anchorman, Pochettino has only three senior centre-backs.

Milos Veljkovic joined Bundesliga side Werder Bremen on the final day of the January window, while Federico Fazio moved to Sevilla on loan ahead of a possible permanent move to the Spanish side in the summer.

A Tottenham recruitment source has told Football Insider that the club are in the market for replacements in the centre-back position.

One player they are closely monitoring is 22-year-old Lyon defender Samuel Umtiti

A report in French sports daily L’Equipe claims Spurs have been so impressed with the versatile youngster that they will “imminently” table a bid.

Umtiti’s possible arrival at White Hart Lane would certainly add to an already capable squad with Wimmer impressing alongside Alderweireld during Vertonghen’s prolonged absence from February until April.

Wimmer filled in for Vertonghen for nine league games in which Tottenham lost one and conceded just six goals.

However, the Austrian remains the only senior back-up centre-back to the first choice duo and Pochettino his keen to rectify this shortfall even though he has high hopes for teenager Cameron Carter-Vickers.

Even if Tottenham do not catch Leicester and steal the trophy from their grasp in the final four league games of this season, the club are keen to put the foundations in place for an annual title challenge.

In other Tottenham news, Spurs are battling with Arsenal to sign the ‘next Riyad Mahrez’.