Russia on Sunday declared a state of emergency in Crimea after four electricity pylons were reportedly blown up, cutting off Ukraine's power supply to the peninsula.

Yuri Kasich, a deputy head of Ukrainian state-run energy company Ukrenergo, said Sunday night that Ukraine's maintenance crews were ready to restore electricity supply to Crimea within four days if they are granted access to the site where the damaged power lines are located.

He added that the site is currently controlled by "unknown people," who have blocked access for the maintenance crews.

People walk along a street in central Simferopol, Crimea, on November 22, 2015. (AFP PHOTO/Max Vetrov)

The Crimean Federal District energy grid has been deployed to provide electricity from its own thermal power plants, and 13 mobile gas turbines as well as wind and solar power generators are also in place, Russia's Emergency Situations Ministry said Monday in a statement.

"More than 3,000 people and over 1,000 machinery units are involved in organizing alternative energy supplies," said the statement.

According to the Russian Energy Ministry, 178 important social facilities had been connected to reserve energy supply sources on Sunday evening, while other facilities, including 150 schools, 100 kindergartens and 40 heating boiler stations, remained without electricity.

The Energy Ministry said it was monitoring the energy situation in Crimea around the clock and was organizing supplementary supplies of gasoline and diesel fuel.

Neither the Russian nor the Ukrainian side has given any official information on the perpetrators and reasons behind the sabotage so far.