A Russian historian who confessed to murdering and dismembering his ex-student lover was put in pre-trial detention on Monday.

The court appearance came amid calls for an investigation into his alleged abuse of women students.

Oleg Sokolov, a prominent expert on Napoleon, was hauled out of the icy Moika River on Saturday with a backpack containing a woman's arms.

A court in the northwestern city of Saint Petersburg ruled that he should be held in prison for two months ahead of the trial over the murder of his 24-year-old girlfriend and former student Anastasia Yeshchenko.

Sokolov, a professor at prestigious Saint Petersburg State University, has confessed to killing Yeshchenko and dismembering her body, and was formally charged Monday evening.

"I am devastated by what has happened, I repent," Sokolov said in court.

The 63-year-old broke down in tears in the glass defendant's enclosure, covering his face with his hands.

Sokolov lived with the murdered woman for the past few years and the killing took place last week.

Police found more of Yeshchenko's remains in the river on Monday, the Interfax news agency reported.

In court, Sokolov attempted to pin blame on the victim, telling the judge that "she went mad when I mentioned my children" from a previous marriage and "attacked me with a knife".

Sokolov is the author of several books on French emperor Napoleon Bonaparte and often led historical re-enactments of the Napoleonic war in Russia. He received France's Legion d'Honneur in 2003.

He and Yeshchenko co-authored a number of works and liked to wear period costumes, with Sokolov dressing up as Napoleon.

He allegedly shot and killed her during an argument and then dismembered her.

After disposing of the corpse he reportedly planned to take his own life at the Peter and Paul Fortress, one of the former imperial capital's most famous landmarks, dressed as Napoleon.

The horrific case drew fresh attention to pervasive sexual harassment and violence against women in Russia, including in academic circles.

Observers said Sokolov had a history of erratic behaviour and reports surfaced that he had abused another female student, prompting outrage that the university took no action at the time.

The university said Sokolov will be fired over the "monstrous crime" and issued condolences.

More than 30,000 people signed an online petition urging authorities to probe the management of Saint Petersburg State University.

The petition said Sokolov had treated students "in a monstrous way" and cited another female student as saying that he had beaten her, threatened to burn her with a hot iron and kill her in 2008.

The university said in a statement that it was unable to corroborate reports about the 2008 assault, but that Sokolov was "disciplined" for unethical conduct during a lecture last year.

The Kremlin called the murder in the university attended by President Vladimir Putin "a monstrous act of insanity" but sought to portray it as an isolated case.

Putin's spokesman Dmitry Peskov however declined to address concerns over reports of harassment in Russian universities, saying: "What does the presidential administration have to do with it?"

Russia has no specific legislation targeting domestic violence or sexual harassment in the workplace and feminist movements like #MeToo have had little impact in the country.