Celtic have confirmed their interest in signing the £2.5m-rated Vitoria Guimaraes striker Amido Balde and are poised to make an offer, according to the player's agent.

The 22-year-old's agent, Catio Balde, said: "We're waiting. The truth is that Celtic, through their executive director for signings [in other words, chief executive Peter Lawwell], confirmed that an offer will be made, making their interest in the player official."

Celtic watched the former Portugal Under-20 internationalist feature in Guimaraes' surprise Portuguese Cup win against Benfica on Sunday. Balde is seen as one of the revelations of the Portuguese season, during which he has scored nine goals in 19 appearances. The player is one year into a two-year contract having joined Vitoria on a free transfer from Sporting Lisbon a year ago. Vitoria hold 30% of the player's rights, Sporting hold 10% and his agent holds the rest.

It is believed Celtic are stepping up their interest in the player after looking like missing out on fellow Guimaraes striker El Arbi Hillel Soudani, who has instead chosen to move to Dinamo Zagreb.

Celtic were last night waiting for Lech Poznan winger Aleksandar Tonev to decide whether he will join the club. They face stiff competition for the 23-year-old Bulgarian, who has two years remaining on his contract.

Malaga and Werder Bremen are reportedly in the race to sign the £2m-rated winger but Tonev has already stated that he wants to play for a club in the Champions League.