MOSCOW (AP) — Russian civil society organizations say that more than a dozen supporters of opposition leader Alexei Navalny have been detained in Moscow while holding small demonstrations.

The detentions come a day after protests called for by Navalny were held in cities across the country to mark President Vladimir Putin’s 65th birthday. The Interior Ministry said Sunday that 136 people were arrested in Saturday’s demonstrations and that all had been released from custody.

The Open Russia group and OVD-Info, which monitors political arrests, said that Sunday’s detentions took place in Manezh Square, adjacent to the Kremlin, and outside the nearby building of the Duma, the lower house of parliament.

The reports’ figures on detentions differed and there was no immediate statement from police.