Police in Moscow detained more than 20 anti-corruption protesters who took to the streets today in a follow-up of last week's large-scale demonstrations in the Russian capital.

The turnout was much smaller than at rallies last week, when hundreds of protesters including a prominent Kremlin critic, Alexei Navalny, were detained as they went out to demonstrate against corruption, demanding the resignation of Prime Minister Dmitry Medvedev.

Today, plain clothes officials and police detained between 20 to 30 people in central Moscow as they tried to organise a march towards the Kremlin, a Reuters witness said.

Interfax news agency, quoting police, said 29 people were detained for "breaching of public order".

There were some 100 protesters in the centre of Moscow, a significantly smaller group than at last week's protests, reckoned to be the biggest since a wave of anti-Kremlin demonstrations in 2011/2012.

The protests come a year before a presidential election in which Vladimir Putin is expected to run for a fourth term.

"People have some questions and they have not been given any answers. And when people tried to speak out about it, detentions took place," said Ksenia, a student from Novosibirsk in western Siberia who joined in the rally in support of the Muscovites.

Before today's protests, Russian authorities had blocked access to several internet pages promoting what the government said was "a planned illegal anti-government protest" in or near Moscow's Red Square.

The organisers of the rally said they are "young people and ordinary students from Moscow" and have nothing to do with Mr Navalny, who is serving out a 15-day jail sentence for his role in organising the 26 March protests.