Bahrain's main opposition party says one of the detained national team football players has been convicted of participating in anti-government protests in the Gulf kingdom and sentenced to two years in prison.

Al Wefaq party says in a statement that the player, Mohammed Hubail, was convicted and sentenced on Thursday during closed-door proceedings in Bahrain's special security court, set up under martial law that was imposed in March to quell Shiite-led demonstrations against a Sunni monarchy.

At least two of his teammates, including Hubail's brother and Bahrain football star, Alaa, have been in custody since the crackdown began.

More than 150 athletes, coaches and referees have also been suspended for their alleged involvement in protests.