Celtic were last night frustrated in their attempts to bring in another striker before the closure of the transfer window.

As expected, the Parkhead side were successful in finalising a £5.5m deal for the Croatian under-21 internationalist Jozo Simunovic as well as a move for Ryan Christie, while Virgil van Dijk’s £11.5m switch to Southampton was also realised.

It left Celtic with a frantic spell in which to land a forward but having reached midnight last night still empty-handed, it remains to be seen now just how costly their failure to do that will be.

Talks with Steven Fletcher and Michu’s representatives reached a stalemate with both moves believed to have stalled after agreement could not be reached on the salary structure of a loan move.

Internet speculation also linked the Parkhead club with a move for highly-rated 19-year-old Manchester United striker James Wilson but there was little credibility to the rumours, with the Old Trafford club adamant that they had given no serious consideration to the player going out on loan.

While the addition of a defender will be welcomed by the Hoops support, the lack of striking options will be viewed as a significant concern, particularly in light of the forthcoming Europa League campaign.

Leigh Griffiths has been in a decent vein of form since the season began but Nadir Ciftci has yet to find the net for the Parkhead side club. Anthony Stokes was close to being off-loaded to Bolton yesterday in a loan deal only for wages to be the stumbling block in negotiations while Stefan Scepovic has been allowed to head out of loan deal to Getafe.

Should Griffiths pick up an injury it would turn up the heat on the Celtic’s threadbare forward line and there will be a simmering unease within the Hoops support over the failure to add further reinforcements to the forward line.

However, the capture of Simunovic has the potential to be a strong one and certainly his selling club, Dinamo Zagreb believe they will bank further cash further down the line.

Chief executive Zdravko Mamic is convinced Celtic will eventually sell Simunovic to the English Premier League for 20 million Euros – with Zagreb due a 25% cut of any future fee that he may well command.

Mamic said: "We have been well protected in this deal, so we will get a large percentage of his future transfer.

"And you know more or less for certain, Celtic's best players all go to the English Premier League for 20 million Euros.

"So will Jozo.

"When Celtic came to visit Maksimir, they told us they wanted to copy Dinamo and learn from us."

Meanwhile, van Dijk has admitted that Celtic did everything they could to keep him at the club but he couldn’t resist the chance to make the move to the Premiership.

“To get the opportunity to play in the Premier League is unbelievable and I will enjoy it,” he said.

“Celtic did not want me to leave and wanted to extend my contract. The club did everything to keep me and I appreciate that, but I felt the time was right for a new challenge in the English Premier League. I thank everyone at Celtic, the manager and all the staff.

“Celtic is a brilliant football club. It will always be in my heart and I will always be a Celtic supporter myself.”

Elsewhere, Stefan Johansen is awaiting the results of tests this week to discover the extent of a hamstring injury.

Norway are preparing for crucial Euro 2016 clashes this week with Bulgaria and Croatia, but they could have to do without Johansen.

Norway manager Per-Mathias Hogmo said: "Stefan stretched his hamstring in Celtic's game in Malmo.

"He is getting a scan to discover the extent of the injury."