Mancini admits City will not buy or sell in this window

Roberto Mancini, the Manchester City manager, is resigned to the fact that this transfer window will be the first since the club's Abu Dhabi takeover in which no new players will arrive.

The Independent revealed in November there would be no reinforcements for the Italian unless he faced an emergency in one position and today he acknowledged that buying would be "difficult".

Mancini had wanted a new centre-half after losing Kolo Touré to the African Nations Cup and Micah Richards to injury. But director of football Txiki Begiristain is seeking, in an era of relative austerity at the Etihad, to reduce annual losses of £97.9m and guide City towards Uefa financial fair play compliance.

Mancini said he lacks the players to sell Mario Balotelli, despite his frustrations with a striker who is ill again and will not play in today's FA Cup fourth-round tie at Stoke City. The manager's insistence that Balotelli has a three-year contract confirms what the striker's agent told this newspaper on Tuesday: that he will not be negotiating with other clubs to move the Italian, 22, on elsewhere. But Mancini indicated that illness and fitness had contributed to the absence of a player in whom he and his staff have invested a lot of time.

"Mario should work well and try to get his place in the team because at the moment he doesn't play – for many reasons," Mancini said. "I hope he can help us to win some trophies because he has the quality. I think today his performance is so-so but at the same time he can improve because in next four months we have important and crucial games.

"We haven't had any requests about Mario or any other player. Mario has another three years on his contract. We don't have enough players. We are 18 players now and we can't sell any players."

Balotelli's cold meant he only started training on Thursday. Samir Nasri has had a similar illness over the past three weeks but the City manager, who has left the Britannia Stadium with three 1-1 draws in the Premier League and an FA Cup defeat in 2010, said he would never field a weakened side in the tournament.

"In Italy we used to do this. In England the FA Cup is more important. I understand some teams think about staying in Premier League. I will always play my strongest team. When you play on a Saturday it is okay. It is difficult to win one trophy, to win a Double is hard but we will try."