Swans supremo Huw Jenkins claims Hoops chief executive Peter Lawwell called him to ask permission to speak to Martinez, which he refused until he had discussed the approach with the Spaniard.

"I had a call off their chief executive making me aware that they'd like to talk to Roberto," Jenkins told BBC Sport.

"Like I've always done, I refused that until I've spoken to Roberto myself and talked things through."

Martinez, who is currently on holiday in Spain, joined Swansea in 2007 and guided the club to the League One title in his first season, before almost taking them to the Championship play-offs during the recent campaign.

And although Jenkins will discuss Swansea's future with Martinez upon his return, he knows the lure of the Champions League could prove to be a decisive factor.

"I'll probably speak to him (Martinez) between now and Wednesday but later on in the week he'll be back home to run through his thoughts with me," Jenkins said.

"First and foremost, it's about his position here and how we see that, and we'll consider all that first before any sort of what else he may do.

"I think you've got to respect that type of club Celtic are and what opportunities exists - perhaps not in the League but certainly in the Champions League - and the size of the club.

"Naturally, I suppose that interest would require anybody to sit and consider their position.

"It's basically up to him how he sees it, I think there's certainly no possibility in us forcing any issue. Roberto has got to consider his future and where his commitment lies."

Martinez, who still has three years remaining on his contract with Swansea, played in Scotland for Motherwell and has also been linked with a move to Wigan.

At 35, he is one of the youngest managers in British league football.

Gordon Strachan quit as Celtic boss a week ago and Burnley's Owen Coyle was immediately installed as the favourite to replace him.

Lawwell reportedly sounded out Coyle after he led the Clarets into the top flight of English football for the first time in 33 years.

But all parties insisted no official approach was made, as is the case with West Brom's Tony Mowbray, who was the other favourite for the post.

Martinez is therefore the first candidate to be confirmed as being on Celtic's hitlist.