Dukvakha Abdurakhmanov, a deputy prime minister in the Kremlin-controlled Chechen civilian administration, also said on Sunday that more than 200,000 people have gone missing.
Abdurakhmanov's claim could not be independently verified.
The Russian government has not revealed any casualties among civilians in Chechnya during the two wars in the region since 1994.
Casualty estimates vary widely, but many say about 80,000 civilians - 40% of them children - died in the first Chechen war. Countless more have been killed since the conflict exploded again in 1999.
Abdurakhmanov made the statement during a visit to the neighbouring province of Dagestan, where more than 1100 ethnic Avar residents of a Chechen village fled after one villager was killed and 11 others went missing during a recent raid they blamed on Chechen security forces.
Abdurakhmanov and other Chechen officials were trying to persuade the refugees to return home, arguing that Chechens had suffered much greater losses throughout the conflict.
The high casualty figures Abdurakhmanov cited could be part of a pitch to push the reluctant residents of the village to come back rather than a product of a thorough calculation.
"You lost 11 people, while every resident of Chechnya has scores of relatives who have been killed or gone missing," Abdurakhmanov told the village's residents.
Vladimir Putin launched the
second Chechen war in 1999
Russian forces pulled out in 1996 after a disastrous 20-month battle with separatist rebels, leaving Chechnya de facto independent.
The Russian army swept in again in 1999 after Chechnya-based fighters made incursions into Dagestan and after 300 people died in apartment bombings blamed on the separatists.