Moscow warns against protests after Alexei Navalny death: ‘Necessary to warn’

The prosecutor's office in the Russian capital said that it was aware of calls online "to take part in a mass rally in the centre of Moscow".

Moscow on Friday warned people against taking to the streets to protest, hours after the death of leading Kremlin critic Alexei Navalny.

A portrait of opposition leader Alexei Navalny and flowers are seen during a protest in front of Russian embassy in Belgrade, Serbia. (AP)

Images on social media showed people laying flowers at memorials to victims of political repression in honour of Navalny, who Russian authorities said had died on Friday in the Arctic prison colony where he was serving a 19-year sentence.

The prosecutor's office in the Russian capital said that it was aware of calls online "to take part in a mass rally in the centre of Moscow" and said it was "necessary to warn against violating the law".

Protests are illegal in Russia under strict anti-dissent laws, with authorities having clamped down particularly harshly on rallies in support of Navalny.

In Moscow, dozens laid red and white roses at the Solovetsky Stone, a monument to victims of Soviet era repression opposite the headquarters of Russia's FSB security services -- the former home of the feared Soviet secret police.

At least one person was detained for holding up a placard that appeared to say "murderers" on it, according to a video posted by the independent Sota Telegram channel.

A handful of people were also pictured gathering to lay flowers at a bridge next to the Kremlin where Putin critic Boris Nemtsov was killed in 2015.

And Police were filmed dispersing people who had gathered in the snow at a memorial in the central city of Kazan.

Some larger demonstrations also took place in Tbilisi, Yerevan and Belgrade -- home to significant populations of Russians who fled the country following Moscow's military offensive on Ukraine.