A Russian director of an acclaimed series about World War II on Friday slammed a state channel's "crude and petty" censorship of his film, after it aired with crucial scenes missing.

Nikolai Dostal, the director of 11-part series Shtrafbat about penal military units used by the Soviet army, said the latest airing of the film on the Rossiya channel had some controversial scenes and obscene language cut, confusing the plot.

The film, which focuses on the darker side of the Soviet war effort, was made in 2004 and won critical acclaim and several awards, though some politicians called it unpatriotic and disrespectful to the war's legacy.

Dostal complained that the channel applied "inexcusable, unlawful censorship" to his work when airing the film this week, crudely cutting out swear words and several scenes, including one where a soldier rapes a Russian woman. The cuts make the unfolding plot "less convincing," the director said.

"The joy that Russians again watched Shtrafbat was thus mixed with shame and bitterness at such crude, petty, and moralising censorship on your channel," Dostal wrote, addressing Rossiya's director Oleg Dobrodeyev.

Penal battalions in World War II employed convicted criminals and political prisoners and were essentially a taboo subject for decades, although they were used in near suicide missions between 1942 and 1945.

The Shtrafbat series were written using archives and testimony from former soldiers.

Contacted by AFP, the Rossiya channel refused to comment on the censorship allegations.

Dostal's letter comes amid what observers say is a campaign to impose morality laws in Russia, and monopolise the portrayal of history, in an flashback to the Soviet era.

The Russian parliament has already passed in an initial reading a bill to ban obscene language in literature and film.

Another law that was recently proposed by pro-Kremlin lawmakers imposes fines and jail terms of up to five years for "justification of fascism," a broad measure which would punish people who talk about crimes committed by and within the Soviet army.

"This is moral censorship," said journalist and television critic Irina Petrovskaya. "The goal is to cut out any possible insult to public morality, the memory of those who died in the war, the tarnishing of the Soviet army."

"Soon a large part of films that are close to reality will be impossible to show," she told AFP.

["Stock Photo: Saint-Petersburg, Russia – November 4: Military Performance In Celebration Of National Unity Day. Three Soviet Soldiers Standing Near Army Lorry On November 4, 2011 In Saint-Petersburg, Russia." on Shutterstock]