Steward (right) has been Lewis' trainer for more than 10 years

The 38-year-old has not fought since retaining his title with a sixth-round win over Vitali Klitschko in June and Steward claims that could have been his final appearance.

"Lennox won't fight before the new year and almost certainly not after that," Steward told the Daily Express newspaper.

"Lennox won't fight again - I am as sure of that as I can be.

"I am not saying he definitely won't go back, but there is very little chance he will return again.

"Lennox has done all he has to do in the ring. He has won the world title and is the undisputed heavyweight champion in everyone's eyes.

Lewis: I won't fight this year

"He has got nothing left to prove."

Lewis has reduced his number of fights markedly over recent years with his last fight before Klitschko an eighth-round win over Mike Tyson in June 2002.

Responding to Steward's comments, Lewis's ex-manager Frank Maloney said he hoped his former fighter had decided to call it a day.

"What Lennox Lewis has achieved is unbelievable for British boxing," Maloney told BBC GMR.

"But he's got nothing else to prove. All he can do is damage his legacy. The mind might still be willing but, at 38, the body's getting weaker.

"There's no-one out there for him and he should retire and enjoy life".