Real Mallorca defender Ivan Ramis
The agent, Javier Diaz, believes the two sides will reach agreement before the deadline.
"The negotiations are continuing and the gap between the sides is narrowing," said Diaz, in reference to reports that Celtic have had a 1.5m bid rejected already.
"I am hoping an agreement can be reached," said Diaz. "Celtic are a massive club and Ivan would be very keen to play there."
Mallorca are seeking around 3 million for the 25-year-old, who would be a direct replacement for Stephen McManus following the Scotland defender's loan move to Middlesbrough.
Scott McDonald's future at Celtic should also be clarified today, with Mowbray admitting at the end of last week that his top scorer could be sold. West Ham and Middlesbrough have both shown interest in the 3.5m-rated striker, although West Ham manager Gianfranco Zola maintains he has not made a bid.
Middlesbrough manager Gordon Strachan has also looked at McDonald, but has made a definite move for Aberdeen striker Lee Miller. The Pittodrie club confirmed yesterday that a bid has been received from Middlesbrough for the 26-year-old, who is out of contract in the summer.
Reports claim Middlesbrough have tabled a bid of 500,000 for the Scotland international, who manager Mark McGhee recently admitted he would be prepared to sell.
Confirming that an approach had been made by Strachan, McGhee said: "If a deal is done, it will have to be done very quickly. We have to decide whether we want to keep him or sell."
Miller joined Aberdeen in 2006 and finished top scorer last season and during the previous campaign. He has struggled in front of goal this term, netting just four times in 23 games. However, Strachan sees him as a solution to his own side's goalscoring problems, while Miller's sale could free up funds for McGhee to sign Plymouth striker Steven MacLean.
MacLean was one of numerous striking targets picked out by sacked Hearts manager Csaba Laszlo, who failed to get the go-ahead from Hearts owner Vladimir Romanov to sign him. The appointment of Jim Jefferies at Tynecastle has raised speculation that the new manager may try to take Kilmarnock striker Kevin Kyle on loan.
Meanwhile, Paul Hegarty will hold talks today with Dundee United manager Peter Houston about becoming his assistant until the end of the season.
Tannadice legend Hegarty, who had a brief spell as manager in 2002, has been out of work since George Burley was sacked from the Scotland manager's position in November.
Hegarty, who spent 15 years at United during the most successful period in their history, compared his potential homecoming to that of Jim Jefferies at Hearts.
"I'd love to go back," he said.
"It's a bit like Jim going back to Tynecastle. Most of my career was at Dundee United."