"We Confirm the receipt, very recently, of a rogatory letter [an instrument for legal cooperation] from the Russian Federation," an official in the attorney-general’s office told Lusa in response to a question on the subject.

Unlike the Belgian, French and Netherlands authorities, who are seeking Pinto’s collaboration to advance their investigations, particularly into tax evasion, the Russian authorities accuse Pinto of various crimes, according to Portugal’s media.

Pinto, a Portuguese national, was on 21 March extradited to Portugal from Hungary, having been detained there on the basis of a European arrest warrant issued by Portugal’s Central Department of Criminal Investigation and Action (DCIAP).

The grounds for the warrant were his alleged illegal entry into the computer systems of Lisbon football club Sporting and the investment fund Doyen Sports, and the subsequent disclosure of confidential documents, including the contracts of Sporting players and of then coach Jorge Jesus, as well as other contracts signed between Doyen and several clubs.

Pinto is said to have hacked into the computer system of Malta-based Doyen in September 2015; he is also suspected of having accessed emails to and from members of the board and legal department of Sporting, by hacking into the computer system of the club’s sports management company.

During his detention in Hungary, Pinto was assumed to be one of the sources of Football Leaks, an online platform that has exposed cases of corruption and tax fraud in the sport on which he had been collaborating with authorities in other countries, notably France and Belgium.