Klitschko last fought in December 2004 against Danny Williams

The 35-year-old Ukranian retired in November 2005 after failing to recover from a series of injuries and may face Oleg Maskaev on 21 April in Moscow.

"Yes, I'm back," the brother of IBF and IBO world champion Vladimir Klitschko told the German Bild newspaper.

"I have renewed energy and I'm completely fit. I'm ready to get back in the ring."

Last month, Maskaev retained his WBC heavyweight crown with a unanimous decision over Peter Okhello in the first world title fight held in Russia.

Klitschko added: "I have submitted a request about meeting Maskaev to the Russian Federation and expect to hear back from them this week.

"I have fulfilled almost all of my dreams in my life. The only thing that is missing is to be world champion at the same time as my brother.

"This goal has never been any nearer."