NEWCASTLE UNITED’S attempts to sign central-defensive target Kristoffer Ajer have stalled, with Celtic holding out for a £20m fee for the Norway international.

Steve Bruce has been hoping to sigh Ajer all summer, with the 23-year-old having entered the final year of his current contract at Parkhead.

However, while the Magpies started the close season with ambitions of being able to sign the centre-half for a cut-price fee, it has rapidly become clear that Celtic intend to drive a hard bargain.

The Scottish Premier League side are aware of mounting interest in Ajer’s services, and have already rejected a number of offers.

They are understood to have turned down £10m bids from both Norwich City and German side Bayer Leverkusen, and have also rebuffed an approach from Brentford in the last few days.

Brentford are reported to have tabled a £12m initial offer, with a further £3m of payments dependent on a series of clauses, but Celtic remain confident they can secure a better deal.

The Celtic hierarchy are currently understood to be holding out for £20m, a fee that is well in excess of what Newcastle would be willing to pay.

The Magpies had been hoping to recruit Ajer for less than half that amount, so their prospects of pulling off a deal currently appear to be negligible.

Earlier in the summer, Ajer had expressed a desire to leave Glasgow, but he is aware of the current situation and is now willing to remain with Celtic for another season, before potentially leaving as a free agent next summer.

Celtic recently appointed Ange Postecoglou as their new manager, and the Australian would like to retain Ajer as he looks to challenge Rangers for the SPL title next season.