Russian opposition groups marched in Moscow on Sunday on the eve of Vladimir Putin’s return to the presidency.
Some 20,000 people demonstrated against the former KGB spy taking back his old job, a move they say is illegal.
Chess champion Garry Kasparov, the leader of the Other Russia party, said Putin had no right to run for a third time because it violates the constitution.
“We have no intention of recognising the results of the last elections or Putin as the legitimate rule of Russia,” he said.
Sergei Udaltsov, the head of the Left Front, said the protest was a success.
But he added that some people were barred from joining the march and that authorities rubber-stamped its permit at the last possible moment.
Udaltsov would later be detained when the protest turned violent.
A group of protesters tried to move towards the Kremlin, only to be beaten back by riot police wielding batons.
Scuffles broke out and officers arrested 250 people, including leading opposition blogger Alexei Navalny.
Putin was president for eight years until 2008, before he handed the job to Dmitry Medvedev.
Russia’s constitution limits anyone from holding two consecutive terms as head of state.