Widespread reports have linked the Reds with a £12m move for the 20-year-old and they are said to be fighting it out with Bayern Munich for the youngster's signature.
Can left the Bundesliga champions in the summer of 2013, but impressed his former side with his displays for Leverkusen last season.
The midfielder's performances have also seen Reds boss Brendan Rodgers sit up and take note and the Northern Irishman has given the green light for the club's recruitment team to try and snare Can away from the BayArena.
Leverkusen sporting director Voller had admitted that he knows about the Anfield side's interest, but claimed that their pursuit has yet to materialise with a formal offer.
"We are aware of the interest from Liverpool, but we haven't had anything concrete yet," Voller told Bild.
"It's a fact that Emre Can has a certain clause in his contract, but there is no decision imminent.
"I have been in touch with Karl-Heinz Rummenigge about Emre Can and Bayern are of the opinion that it would be good for the player to remain at Bayer Leverkusen."
Rodgers, who signed a new contract with the five-time European Cup winners earlier this week, is keen to beef up his squad ahead of a new season that sees them return to the Champions League for the first time in five years.
Alongside Can, the Reds have been linked with a £20m move for Southampton captain Adam Lallana, while Ukraine international winger Yevhen Konoplyanka could also be the subject of a fresh bid, following their failure to land the wide-man in January.
Rodgers is keen to recruit a top-class left-back, and the Reds boss has been linked with a move for Chelsea's free agent Ashley Cole and Sevilla's Alberto Moreno.