Ashworth insisted that there is no pressure to sell Olsson, who joined the club from NEC Nijmegen four years ago.
He said: "He is one of our most important players and we would like to keep him like we did last year with Youssouf Mulumbu and Peter Odemwingie last year.
"We're trying to build a squad not sell our best players.
"There wasn't a huge outlay on the transfer so we don't need to make a huge amount of money back if he decided to run the contract down.
"We would have to weigh it up and consider whether there is a transfer offer that meets the value of either getting a replacement or losing Jonas for the season."