Trotters chairman Phil Gartside has revealed that the club are waiting on a response from both players after several first-team players left the Reebok Stadium last week.
"It was important that we kept what was going to be a Premiership squad together," Gartside told Sky Sports News.
"The only disappointment is Nigel Reo-Coker decided to invoke his get-out clause. You move on and we'll replace him with somebody else that's going to be as good, if not better.
"Martin Petrov's contract is already in place and his contract runs out at the end of next season. He's indicated that he's more than happy to stay.
"Zat Knight and Jussi were out of contract this year and we've made them offers. Watch this space, we're still waiting for replies from them."
Bolton finished 18th in the Premier League and were relegated to the Championship on the final day of the season.