Seven Sporting CP stars have been allowed to terminate their contracts, according to the Portuguese Players' Union.

The Union have stated that the players - including four of Portugal's World Cup squad - cited "just cause" as a reason for the termination, after a group of 50 masked fans attacked players and staff in May following the club's failure to qualify for the Champions League.

Rui Patricio, William Carvalho, Gelson Martins and Bruno Fernandes - who are all with Portugal in Russia - are all now available on free transfers, as are Ruben Ribeiro, Bas Dost and Daniel Podence.

At the time of the attack, in which Dost was injured, goalkeeper Patricio said: "I was the victim of physical and psychological violence, so in order to preserve my personal and professional dignity, I wish to end the contract that ties me to Sporting."

Patricio has been heavily linked with Wolves, midfielder William Carvalho was believed to be close to joining West Ham last season and winger Martins has been watched by both Arsenal and Liverpool, who are also thought to be watching Fernandes.