GROZNY, November 21 (RIA Novosti) - Commander of the United Group of Forces in the North Caucasus strongly condemned Monday the murder of three civilians in the village of Staraya Sunzha in Chechnya last week.

"The murder was committed by a serviceman who had been convicted for crimes twice [before]," General Yevgeny Lazebin said at a Chechen Security Council session.

Earlier, a military prosecutor said three servicemen had been detained and admitted their guilt in relation to the case.

Lazebin called the incident in the Starye Atagi village, which came under mortar fire on November 9 and wounded five people due to a targeting error, "a criminal mistake".

A demonstration took place in Grozny Monday, with protesters demanding punishment for those guilty in the two attacks.