Roberto Mancini has given vent to his frustration over Manchester City's failure to sign Robin van Persie from Arsenal and has made it clear he holds the club's football director, Brian Marwood, accountable.

Mancini is keen to improve his squad and build on last season's breakthrough title triumph and he has targeted Van Persie, who wants to leave Arsenal, as the player to make the difference. The manager wanted to see quick and decisive action from City's transfer market dealers, led by Marwood, but he has been irritated by their more painstaking approach. Manchester United and Juventus are also jostling for Van Persie's signature and they appear to have stolen a march on City.

Mancini spoke out before City's friendly against Arsenal in Beijing on Friday and, although he did not name Marwood, it did not take a detective to pick up on the club's internal tensions. "For this question, speak to the man in charge," Mancini said, when asked about Van Persie. "I am not in charge of this. It is important [to get players quickly] because, after what we did last year, we must continue to win. This year will be harder than last, so we need to improve our team. We have a man who works for this and we hope that they can do a good job."

The climate at City is different this summer. In recent transfer windows the club have paid huge sums to acquire their targets, sometimes paying over the odds and using their financial clout to catch up with the elite in a hurry. But there has been a change of tempo – and not only because there is an acute awareness of the incoming Financial Fair Play legislation.

City are aware that they have to move on some of their unwanted strikers, including Emmanuel Adebayor, Roque Santa Cruz and, possibly, Edin Dzeko or Carlos Tevez. Given the players' massive salaries, that is proving difficult and time-consuming.

Adebayor has been close to a permanent move to Tottenham Hotspur for some time, the fee of £5.5m having been agreed between the clubs, but his personal terms have not been finalised. Adebayor has one year remaining on his City contract, which pays him £170,000 a week. Dzeko, who is of interest to Milan and Juventus, gets £4.5m a year after tax.

Mancini does not accept City's more prudent style. To him the business should be simple; he gives Marwood a name or names and the signing follows swiftly. Mancini's position has been cemented not only by the title win but by the new five-year contract he agreed at the beginning of the month, although he has never been slow to voice his anger at what he considers to be unnecessary delays in bringing in players.

City have yet to make a signing this summer and Mancini is fearful that, if United did land Van Persie, he could power them to new heights. City had appeared favourites to sign him but United and Juventus are now the front-runners. All three clubs have had offers rejected by Arsenal, with Juventus indicating lately that they are prepared to go close to the £20m asking price. United will also bid again.

This article was amended on 27 July. The original said Craig Bellamy was still a Manchester City player. This has been corrected.