Russian prosecutors on Wednesday demanded an eight-year prison sentence for artist Alexandra Skochilenko, who last year swapped supermarket price tags for statements criticising Moscow's military offensive in Ukraine, independent media reported.

The 33-year-old artist and musician has been in detention since April last year, when she was arrested for changing labels in a Saint Petersburg supermarket with messages against Russia's large-scale intervention in Ukraine.

"The prosecution has asked for eight years," the independent Mediazona website reported, citing a journalist in the courtroom in Saint Petersburg.

Skochilenko, who is known mostly by her diminutive Sasha, was accused of spreading disinformation about the Russian army.

The legislation, which carries a maximum term of 10 years behind bars, was adopted after Moscow deployed troops to Ukraine in February 2022 and has been used to stifle criticism of the conflict.

Skochilenko has been on trial despite a number of health conditions, including celiac disease and a congenital heart defect. 

Her mother Nadezhda Skochilenko told AFP last month that "a real prison term would just be a catastrophe for Sasha". 

Mediazona published a photograph of Skochilenko in the defendant's box, wearing a colourful T-shirt with a peace sign on it. 

The website reported that German diplomats and some cultural figures were present at the hearing.

Her price tag messages included descriptions of people hiding from Russian bombing in Ukraine's Mariupol, as Moscow introduced a ban on criticism of its offensive. 

She was arrested after a shopper reported the price tags to the police.

"The words about how Russia attacked Ukraine are false," Mediazona quoted the prosecutor as saying. 

"The aim of the special military operation was to protect the citizens of Donbas from aggression," the prosecutor added, using the Kremlin's name for its offensive.

Thousands of Russians have been detained, jailed or fined for opposing the conflict.