Celtic have fended off competition from Charlton Athletic to sign Scotland defender Steven Pressley.

The 33-year-old's agent, Blair Morgan, has revealed that Pressley opted to join the Scottish champions due to the promise of playing in the Champions League next season.

Because he played for Hearts in Europe this term, Pressley is cup-tied for the current Champions League competition.

Despite 33-year-old Pressley undergoing a medical with English Premiership side Charlton Athletic on Wednesday, Celtic manager Gordon Strachan continued to talk with the player and his representative.

Pressley reached a deal to leave Hearts on 9 December, six weeks after criticising the way the club was being run.

However rather than joining Charlton's battle to avoid relegation, Pressley will step into a Celtic team who have a 15-point cushion at the top of the Bank of Scotland Premier League.

Morgan said: 'It was a really, really difficult decision.'

'He had two fantastic offers from two good clubs, but the lure of European football next season won the day.'

Pressley has signed an 18-month deal, keeping him at Celtic until the end of the 2007-08 season.

He cannot play until the new year, as the deal has occurred outside of the transfer window, but the centre-back could make his debut in the home match against Kilmarnock on January 2. 

Pressley said: 'I'm absolutely thrilled and honoured to join Celtic. It's a fantastic opportunity for me at this age.

'There are plenty of challenges. There is the opportunity to win silverware here at Celtic Park. In eight-and-a-half years at Hearts I got the opportunity to do that only once and it was a fantastic feeling.

'Here there are expectations to do that on a regular basis and an added pressure with that but one I'm looking forward to.

'Winning the cup last year gave me a taste of it and once you have a taste you want more.'

Pressley also admitted the opportunity to play Champions League football had influenced his decision.

He said: 'It was a big draw. Obviously as I played for Hearts in the qualifying rounds I'm unable to play any part this season. Hopefully there will be the opportunity next year.'

Strachan believes Pressley is the "leader" that the centre of his defence needs.

The Hoops have Gary Caldwell and Bobo Balde on the long-term injury list with John Kennedy still some way off a comeback from his absence of almost three years.

Strachan said of Pressley: 'He has worked hard. I've known him since he was a kid and he has got better every year, not only as a player, as a man.

'He has shown over the last few years he is an exceptional leader. He has presence, not only on the field but in the dressing room.

'We need these kind of people at our club. Our centre-halves are young, we need a leader.

'My midfield players can look at (Shunsuke) Nakamura and (Neil) Lennon to see how midfield play is meant to be done.

'It is easy for me when players can watch good players in their position.

'Steven will be the perfect example on and off the pitch of how to deal with being a centre-half and a Celtic player.'