Posters expressing support for Dzhokhar Tsarnaev, who is charged with last month’s bombings at the Boston Marathon, have been put up on walls in Chechnya’s capital, Grozny.

It is not clear who is behind the posters declaring Dzhokhar Tsarnaev “not guilty”, which appeared after Russia’s May Day celebrations.

The posters show pictures of Dzhokhar Tsarnaev and his mother, Zubeidat Tsarnaeva, and include an appeal for online donations.

The Tsarnaev family are ethnic Chechens but have lived mostly outside Chechnya.

Residents of Grozny say the posters most likely came from someone trying to make money out of the Boston Marathon bombings.

Posters expressing support for Dzhokhar Tsarnaev have been put up on walls in Chechnya’s capital, Grozny

Dzhokhar Tsarnaev’s elder brother Tamerlan – a fellow suspect – was killed during a clash with police three days after the April 15 bombings, which killed three people and wounded 264.

Reports say the Tsarnaevs lived for years in Kyrgyzstan – in Central Asia – and Dagestan, another Russian republic in the North Caucasus which borders Chechnya.

In the 1990s, Russia’s war in Chechnya spilled into Dagestan. It is now more violent, and is experiencing an Islamist insurgency and harsh police crackdown.

Pro-Tsarnaev leaflets have also appeared in Bishkek, the Kyrgyz capital, Russia’s Interfax news agency reports. Police are trying to find out who stuck them on the walls of underpasses in the city centre.

The posters in central Grozny follow an earlier campaign there in support of the Tsarnaevs. The authorities removed the earlier ones, which appeared on April 24.

The latest posters in Grozny say: “This is Dzhokhar Tsarnaev, a 19-year-old lad accused of a terrorist attack in Boston. But as many people now know, that is a groundless accusation, there is absolutely no evidence against him.

“Now he is in a serious condition, in a prison hospital, he needs medical and legal help. Dzhokhar’s parents ask you for help, to collect money for their son, whom they cannot lose, as they have already lost the older son, cruelly, unjustly. We will be grateful for any help, in the name of the Almighty do not remain indifferent.”

The message includes a number for the Russian online payment system, Qiwi Wallet, and the Tsarnaev family address in the social network, VKontakte.

According to Chechnya’s Moscow-backed President Ramzan Kadyrov, the Tsarnaevs spent little time in Chechnya, a republic devastated by war between Russia and separatist rebels in the 1990s.

Since then, Grozny has been rebuilt and now boasts skyscrapers and a huge central mosque.