MOSCOW (REUTERS) - Three people were killed and two dozen were wounded on Saturday in a mass brawl at Moscow's largest cemetery that witnesses said was sparked by rivalry between ethnic groups battling for control of the burial service business.

About 200 people, some armed with guns and other weapons, took part in the clashes at the vast Khovanskoye cemetery in southwest Moscow and more than 90 people were detained after riot police broke up the brawl, police and witnesses said.

Moscow's city health department said three people were killed and 23 were hospitalised, four of whom were seriously injured.

Pictures posted on social media showed young men wielding iron rods, spade shafts and baseball bats as they rushed into the fighting.

Reuters witnesses saw a young man's body lying on the pavement near an overturned car as a forensic expert bent over it.

About 10 mainly young men lay handcuffed on the ground while police armed with Kalashnikov rifles looked on.

The RIA news agency quoted a cemetery official as saying people from Russia's North Caucasus regions of Chechnya and Dagestan had attacked migrants from ex-Soviet Uzbekistan and Tajikistan working there, attempting to take over their jobs.

With Russia's economy battered by Western sanctions and low prices for its oil exports, migrants struggle to find work and ethnic criminal groups add to social tensions.

Quoting a police source, TASS news agency said ethnic Chechens, Dagestanis, Uzbeks and Tajiks were among those detained.

Tajikistan's Interior Ministry will send to Moscow its top expert in battling organised crime in the former Soviet Union to help investigate the incident, Russian news agencies quoted Russian police spokeswoman Irina Volk as saying.

Moscow mayor Sergei Sobyanin said on his Twitter account that none of those responsible would go unpunished.