Ruling United Russia party silences critics, cracks down on poll monitors and offers cash to voters as its support slumps

The Russian government has silenced opposition voices, approved cash payouts to potential voters, and made it nearly impossible to monitor the polls as it prepares for parliamentary elections next month that the opposition has warned will be marred by fraud.

United Russia, the ruling party that has supported Vladimir Putin through nearly his entire presidency, is expected to maintain a majority of the seats in the next Duma, despite state polling that shows that just 26% of Russians are ready to vote for the party – its lowest rating since 2008.

Exclusive: Russian opposition leader likely to infuriate Kremlin with letter dictated from behind bars

• Alexei Navalny: Only action against corruption can solve the world’s biggest problems

The jailed Russian opposition leader Alexei Navalny has written from behind bars to urge western politicians to take meaningful action against global corruption and to impose personal sanctions against oligarchs “in the entourage of Vladimir Putin”.

Writing in the Guardian before the first anniversary of his poisoning on 20 August last year, Navalny lambasts western leaders for not doing more to tackle what he admits is a “tricky issue”. He says his own survival after being exposed to novichok was only down to incompetence and corruption inside Russia’s FSB spy agency.

Action comes as Kremlin increases pressure on opponents and critics ahead of parliamentary elections

Russian authorities have restricted access to Alexei Navalny’s website and those of dozens of his close allies, the imprisoned opposition leader’s team has said.

The action came as the government increased pressure on opposition supporters, independent journalists and human rights activists ahead of the country’s parliamentary election. The September vote is widely seen as an important part of Vladimir Putin’s efforts to cement his rule before a 2024 presidential election.