Police in Saint Petersburg on Saturday arrested a prominent Russian historian on suspicion of murdering a former student after he was hauled out of a river with a backpack containing a woman's arms, authorities said.

Russian police block a bridge over the Moika River during searches operation conducted by Russian emergency rescuers and police investigators on the river, in Saint Petersburg, on Sunday. Photo: AFP

Local media in Saint Petersburg reported that university professor Oleg Sokolov was drunk and fell into the river as he tried to dispose of body parts.

Police reportedly then went to Sokolov's home where they discovered the decapitated body of Anastasia Yeshchenko, 24, with whom he had co-authored a number of works.

"A 63-year-old man was rescued from the River Moika," investigators said in statement.

The arms of a woman were discovered in his backpack, the statement said, adding that the detained man was suspected of murder.

Investigators did not name the man but police speaking to AFP identified him as Sokolov.

The historian is the author of books on French statesman and military leader Napoleon Bonaparte and had acted as a historical consultant on several films.

He received France's Legion d'Honneur in 2003. Sokolov was also a member of France's Institute of Social Science, Economics and Politics. The society announced that he had been stripped of his position on its scientific committee on Saturday. "We learn with horror ... the atrocious crime of which Oleg Sokolov is guilty...," it said. "We could never imagine that he could commit such an odi¬ous act," the statement added.