Constant speculation as to whether Kevin de Bruyne will join Manchester City is unsettling both VfL Wolfsburg's midfield star and his team-mates, club boss Klaus Allofs admitted Sunday.

According to British media reports, City are poised to raise their offer to £50 million (69.9m euros, $78.1m) to meet Wolfsburg's asking price for the Bundesliga's player of the year for 2014/15.

The deal would be a club record for City, surpassing the £49 million they paid for Liverpool's England midfielder Raheem Sterling, while Wolfsburg paid Chelsea just £17 million for De Bruyne in 2014.

But after failing to shine in Wolfsburg's season-opening 2-1 league win over Eintracht Frankfurt last Sunday, De Bruyne put in another below-par performance in Wolfsburg's 1-1 draw at Cologne on Saturday in the Bundesliga.

Last season's runners-up needed a late Nicklas Bendtner goal to equalise and Allofs, Wolfsburg's director of sport, said the uncertainty about De Bruyne's future has been a distraction for both the player and the team.

"It's true that we are influenced by it, but we can't complain and we have to learn to deal with such disturbances and distractions," said Allofs.

"Kevin's performances has corresponded with that of the team, but that's a good sign that he is still part of the side.

"It doesn't mean that he has played particularly badly, just that he hasn't produced his best performances on two occasions.

"I will not accept it as an excuse. We can't just blame everything on the current situation."

The Belgian has been outstanding for Wolfsburg since arriving from Chelsea in January last year and Allofs does not expect the City speculation to end until the transfer window closes on August 31.

Before then, fifth-placed Wolfsburg host Schalke, who are currently third, next Friday in a key league match.

"The question I'll answer by August 31 at the latest," Allofs replied when asked if De Bruyne will remain a Wolfsburg player.

"If you ask me now if he'll play on Friday against Schalke, the answer as of today is 'yes'."