Manchester City chief executive, Ferran Soriano, accused of spying on Barcelona

The Manchester City chief executive, Ferran Soriano, has become embroiled in allegations that he spied on the internal emails of Barcelona employees.

It is believed that the 45-year-old, who took over from Garry Cook last August, may be the subject of a campaign emanating from Barcelona, where some are seeking to destablise him and the club's former sporting director Txiki Begiristain. Both men left the club when Juan Laporta – a Soriano ally – was ousted as president by Sandro Rosell.

Under Spanish law, virtually anyone can trigger an investigation by lodging a complaint against the administrators of a football club. As of Tuesday night, there had been no contact between prosecutors and Soriano since their initial fact-finding investigation which started three years ago. Cook left City after it was discovered he had sent an offensive email.

Catalonia's senior prosecutor has found that when Soriano was a vice-president of the club he ordered a cyber intelligence company, Cybex Experience, to embed a device in the server of the club's internal computer, enabling all internal emails containing any one of 100 keywords to be monitored, on a total of 20 computers across every department of the club, between mid 2005 and 2008. The senior prosecutor said that "stopping leaks to the press" was the motivation behind the installation of the surveillance software – called Encase Enterprise – but eventually Cyber Experience recommended covering the whole internal network.

City declined to discuss the prosecutor's findings, which have surfaced in the Catalan media after the conclusion of her investigation. But the club's view that there is a deliberate campaign to destabilise Soriano is supported by a sequence of reports claiming that Soriano has gone back on an "honourable" pledge not to take players from Barcelona, by trying to sign Cesc Fabregas, Sergio Busquets and Pedro Rodriguez – which they have not.

There have also been reports that City are trying to gazump Barcelona for the services of Neymar. The Premier League champions are monitoring his situation, like most clubs who are capable of signing him, but have accepted that the 21-year-old will become a Barcelona player this summer.

The prosecutor found that Soriano signed off the invoices to Cybex Experience. The suggestion is that there were enough monitored words to fill a 15-page report, with a copy of each email subsequently sent to a mailbox. Cybex analysed them and passed their findings back to the executives who hired them. Anyone with an fcbarcelona.cat email address was monitored, though probably not the players.

Another company, M3, is understood to have been brought in to establish where a number of leaks were coming from in 2009.

The prosecutor also concluded that Barcelona paid a private detective agency to compile files on four presidential candidates at a cost of €16,240 each, without their knowing, at a time when Rossell was seeking to replace Laporta. There is no suggestion this is linked directly with Soriano.