A Moscow court has left a 19-year-old Putin critic in pre-trial detention until September, as the Kremlin uses sweeping security measures to drown out dissent during the World Cup.

As her parents stifled tears in the stuffy courtroom, judge Anatoly Kostyukov turned down veterinary student Maria Dubovik's plea for home arrest despite complaints about her worsening health.

She and five others who disparaged Vladimir Putin's government in private chats were jailed in March and face 10 years in prison for “organising an extremist group”. They include Anna Pavlikova and Vyacheslav Kryukov, who were 17 and 19 at the time of their arrest.

Four more defendants are under home arrest.

A 2017 presidential decree banned all rallies during the World Cup not approved by local authorities, and the government has begun implementing heavy security for the event.

But critics argue state agencies are clamping down on all forms of dissent ahead of the start of the competition next week.