The Mail on Sunday says Mancini has not been fobbed off by last weekend's £12m signing of youngster Jack Rodwell and wants three ready-made first-team players before the end of the transfer window, including Liverpool defender Daniel Agger and Roma's Italy midfielder Daniele De Rossi.
City start the defence of their Premier League crown against Southampton on Sunday, with Mancini still fretting about the lack of his club's transfer activity compared to Manchester United, who have captured Footballer of the Year Robin van Persie and Japan midfielder Shinji Kagawa from the Bundesliga champions Borussia Dortmund.
"'I'm happy with Jack (Rodwell) because he is young and a really good player. But we need to have other players," said Mancini.
"When the Champions League starts, we will be playing every three days for 10 months. This is not easy if we don't have players."