The move is expected to lead to power shortages in some countries
Uzbekistan is withdrawing from a Soviet-era power grid which linked it to other countries in Central Asia.
The country has spent $1bn (£607m) on new power lines, enabling it to become independent of the system.
But Tajikistan and Kyrgyzstan, the poorest nations in the region, rely heavily on gas and electricity supplies sent through the grid.
Critics say Uzbekistan's move is politically motivated and the countries are now likely to experience shortages.
Tajikistan and Kyrgyzstan are both working on large hydroelectricity projects, which Uzbekistan says will restrict the flow of water in Uzbek territory.
This would be damaging to the Uzbek cotton production industry, on which its whole economy is based.
The new Uzbek power distribution system will allow the country to transmit electricity without using power lines in neighbouring countries.
The head of Uzbekistan's state utility company, Uzbekenergo, told state media the shared grid had been "a real threat to the stability and safety of Uzbekistan's own power system".
"Uzbekenergo sees no possibility of continuing to operate," Esso Sadullayev was quoted as saying by the Associated Press news agency.
Tajikistan and Kyrgyzstan both experience bitter winters with many people living in adequate housing, so any shortage of electricity and gas are expected to be harshly felt.
The power grid was set up in a time when the states shared resources freely across their borders.
But correspondents say the failure to continue to do so has been a source of tension between the former Soviet states.
The mismanagement of energy and water resources has also become one of the biggest problems in Central Asia.