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By Andrew Osborn
MOSCOW, Aug 9 (Reuters) - Thousands of Russians are expected to rally again in Moscow on Saturday to demand free elections despite a police crackdown and a refusal by authorities to meet protesters' demands.
It will be the fourth consecutive week when large numbers of people have taken to the streets of the Russian capital to demand opposition-minded candidates be allowed to run in a Moscow election next month - something the authorities have so far refused to allow.
Saturday's protest has been authorised by city authorities, but a similar protest a week earlier was not and police detained more than 1,000 people, sometimes violently, part of one of the biggest crackdowns on dissent in recent years.
Investigators have opened criminal proceedings against about a dozen people for what they term as mass civil unrest in relation to previous protests, a crime that carries a heavy jail term. They have also opened a money-laundering investigation into Kremlin critic Alexei Navalny's anti-corruption foundation.
Some pro-Kremlin politicians and officials have suggested that the West has helped orchestrate the protests. Navalny and at least seven of his allies are currently in jail for breaking protest law.
Several famous musicians have said they want to perform at Saturday's protest, something the authorities have rejected.
Some opposition activists have also said they plan to walk through central Moscow afterwards, setting up a possible confrontation with police who say they will not tolerate trouble.
Navalny allies have also called for a nationwide protest on Saturday though it is unclear how many people that might attract.
The focus of protesters' anger is a prohibition on a slew of opposition-minded candidates, some of whom are allies of Navalny, from taking part in a September election for Moscow's city legislature.
That vote, though local, is seen as a dry run for a national parliamentary election in 2021.
Authorities say the opposition candidates failed to collect enough genuine signatures to register.
The excluded candidates say that is a lie and insist on taking part in a contest they believe they could win.
The ruling United Russia party's rating is at its lowest since 2011 and President Vladimir Putin's own rating has fallen due to discontent over falling living standards.
At well over 60 percent, it is still high compared to many other world leaders however and last year the 66-year-old former KGB intelligence officer won a landslide re-election and a new six-year term until 2024. (Additional reporting by Tom Balmforth, Maria Kiselyova, Maria Tsvetkova and Gleb Stolyarov Writing by Andrew Osborn Editing by Angus MacSwan)