Moscow, Jul 9 (IANS/RIA Novosti): Russia is holding a day of national mourning Monday for the victims of devastating flash floods that hit the southern Krasnodar region over the weekend.

At least 171 people, many of them elderly, were killed in Russia's worst floods in living memory, officials say.

The town of Krymsk was worst hit, after heavy rains dumped as much as 30 cm of water Friday night, the region's average rainfall for two months. The authorities admitted people were given little warning about the impending disaster.

"Not all of the population was warned in due time," Emergencies Minister Vladimir Puchkov told a meeting Monday. "Mistakes were made by local authorities and certain departments."

President Vladimir Putin ordered an inquiry after flying over the affected area in a helicopter Saturday. Police have launched a separate investigation into whether the deaths were caused by negligence.

It was the worst disaster since Putin was elected for a third term in a disputed poll earlier this year.

TV footage showed thousands of homes in the town almost completely submerged, with residents forced to take refuge in trees or on rooftops.

Krasnodar region Governor Alexander Tkachyov has dismissed allegations that the seven-meter waves flood was caused by the opening of sluice gates at a local reservoir.

Most of the deaths occurred in Krymsk, a town of some 57,000, but casualties were also reported in the Black Sea resort of Gelendzhik and the port town of Novorossiysk.

More than 22,000 people were affected by the floods, and around 5,000 homes inundated, authorities said.