Southampton have been in discussions with Celtic over the potential signing of defender Virgil van Dijk, BBC Scotland has learned.

But no offer has yet been made for the 24-year-old Dutchman from the English Premier League club.

Van Dijk is one of many targets Saints are pursuing as they look to recruit one more central defender before the transfer window closes.

Saints lost Belgium international Toby Alderweireld this summer.

The 26-year-old was on loan to Southampton from Atletico Madrid last season, but Tottenham Hotspur beat their Premier League rivals to his permanent transfer in

an £11.5m summer move.

Former Celtic defender Jos Hooiveld was released and has joined AIK Stockholm, 20-year-old Jordan Turnbull has been farmed out again to Swindon Town, while Romania centre-back Florin Gardos

is out injured for seven months.

Southampton midfielder Victor Wanyama

Victor Wanyama joined Southampton from Celtic for about £12.5m in 2013

Saints last month

signed Steven Caulker

on loan from relegated Queens Park Rangers, but manager Ronald Koeman wants to add more cover in central defence.

In addition to Hooiveld, Southampton have in recent seasons bought midfielder Victor Wanyama and goalkeeper Fraser Forster from Celtic.

There was speculation linking Van Dijk with a move to the English top flight last summer, but the Dutchman who joined Celtic for £2.6m from Groningen remained for a second season at Celtic Park.

Asked about reported interest from Southampton this summer, manager Ronny Deila insisted there had been no bid from the St Mary’s outfit.

Deila insisted that he is

not interested in selling

Van Dijk and that the Dutchman would not be sold while Celtic were still attempting to qualify for the Champions League group stage.

The Norwegian’s side face Swedish champions Malmo in the play-off round, with the first leg on 19 August in Glasgow and the second a week later.

Southampton are in the Europa League play-off round, with their opponents being Midtjylland of Denmark.