MOSCOW (Reuters) - Russian police on Thursday detained Lyubov Sobol, an ally of jailed Kremlin critic Alexei Navalny, her lawyer said, after she urged Navalny’s supporters to take to the streets on Saturday to call for his release. Her lawyer gave no reason for her detention in a short post on Twitter, but authorities have said the planned protests are illegal and that they will take action against people who encourage others to go. Navalny, President Vladimir Putin’s most prominent critic, was detained at the weekend and later jailed for alleged parole violations after flying back to Russia for the first time since being poisoned by a military grade nerve agent.