Bulgaria international Mihaylov, 22, was signed by the Reds in 2007 and loaned out to FC Twente in a bid to secure a work permit.
He has since joined Twente on a permanent deal but, as he has now become a regular for his country, he has claimed Liverpool retain an option to take him back to Anfield.
"Liverpool are a huge club," he told Darik Radio. "It wasn't possible to get a work visa when I went there but now there'll be no such problems because I'm playing regularly in the national team."
Asked about Liverpool's option to re-sign him, Mihaylov said: "I think it's absolutely real. The option was made when Rafa Benitez was in charge."
Mihaylov believes Liverpool will be in need of a new goalkeeper in the near future as Reina has a desire to return to his home country.
"I know from my agent Pepe Reina wants to go back to Spain," he said. "His desire dates back one or two years.
"It's not difficult to see this. I know him well - he's one of the best 'keepers in the world but his current form is not as it should be in a club like Liverpool."