CELTIC are set to strengthen their squad with the signing of Ryan Christie and Jozo Simunovic before the summer transfer window closes today.

The Scottish champions agreed fees totalling just under £5 million with Inverness Caledonian Thistle and Dinamo Zagreb for Christie and Simunovic respectively.

Christie, the SFWA Young Player of the Year last season, and Simunovic, the Croatian centre half, both underwent medicals yesterday after finalising personal terms.

Ronny Deila is also still hopeful of bringing in Scotland striker Steven Fletcher on loan from bottom-placed English Premier League club Sunderland until the end of the 2015/16 campaign.

However, the Glasgow club have still to agree a transfer fee with Southampton for their Dutch centre half Virgil van Dijk - they are holding out for at least £10 million for the 24-year-old defender.

Meanwhile, Stefan Scepovic, the Serbian striker who has failed to hold down a regular first team place since joining Celtic for £2.3 million last year, has moved to Getafe in Spain on a season-long loan.

Christie, 20, underwent a medical in Glasgow yesterday after Caledonian Thistle had accepted an offer in the region of £500,000 for the attacking midfielder who helped them finish third in the Premiership and win the Scottish Cup last season.

Simunovic, meanwhile, was examined in Belgium after a fee of around £4 million was settled upon with Zagreb. The 21-year-old may not arrive in this country until after the international break.

Celtic have been tracking the promising player, who is not a first team regular at the Maksimir Stadium, since before the Champions League matches with Malmo as they prepared for Van Dijk to move to England.

Zagreb qualified for the Champions League group stages last week after overcoming FK Skerderbeau in the play-off – a success which meant that Simunovic was deemed surplus to requirements.

Simunovic played against Celtic for Zagreb in the Europa League group stages last season and impressed manager Deila with his performances. He will fight with Tyler Blackett, the Manchester United defender who has joined on a season-long loan, for a place in the first team at Parkhead.

Jason Denayer, who enjoyed a successful stint at Celtic last season, has opted to move to Galatasaray in Turkey from Manchester City on loan for the season despite interest from Deila.

Last week Deila said: "We are working for every opportunity that can happen.

"There are different prospects we are looking at now. There will be a lot of rumours in the next few days. A lot of things going on. On September 1, then we can sit down and see where we are.

"Nothing has changed (with Van Dijk). It’s the same situation. It will be good for him and for us that this finishes on September 1 so we can move on.

"He has a contract here and we want to keep him. We don’t need to sell him. I know there is interest from different clubs so that’s positive.

"I think it’s normal that he’s thinking about what his options are, but he’s happy here. He knows he has a fantastic club but he is also seeing if these other options could take his career to another level."