Russian energy company Gazprom said it has "stopped supplying un-paid-for gas to Ukraine" this morning, according to reports in Russian media.
Gazprom said Ukraine has failed to pay for its gas supplies.
A Gazprom spokesperson told ITV News the company will now require all payments to be made in advance.
Russia's energy giant Gazprom said Ukraine had failed to pay at least part of its gas debts by this morning's deadline and must now pay up front for its energy supplies.
Gazprom said Ukraine has not yet paid for June supplies. The two countries failed to reach a deal on gas prices.
Ukraine and Russia failed to hold expected talks on a gas pricing dispute this morning, despite a deadline for Kiev to pay a $1.95 billion debt by Monday or have its gas supplies cut off.
Russian decision to stop deliveries to Kiev could disrupt the gas flow to the European Union, which receives its energy via Ukraine.
Ukraine and Russia will attempt fresh talks this morning, ahead of a Russian deadline for Kiev to pay a $1.95 billion (£1.15 billion) debt or have its gas supplies cut off.
The two countries failed to end a gas pricing dispute at talks yesterday.
Russia's decision to stop deliveries to Kiev could disrupt the gas flow to the European Union, which receives its energy via Ukraine.
There are fears of gas shortages in Ukraine after Russia announced it would raise its prices. But will that affect the rest of Europe?Read the full story ›
ScottishPower will reduce its domestic gas and electricity prices on January 31 following the measures recently announced by the UK Government to curb non energy costs.
A typical dual fuel household annual bill will reduce by £54, made up of a 3.3% reduction in standard tariffs for dual fuel customers – £42 per annum. It also includes a universal rebate to be paid to customers in line with the government timetable - £12 per annum.
This reduction will bring the average annual bill for a dual fuel customer paying by monthly direct debit down to £1,199 per annum. It should benefit 2.2 million households.
A number of British consumers may be able to cut their energy tariffs from December under rules proposed by regulator Ofgem which it hopes will encourage competition.
Lawrence Slade from the industry trade body Energy UK has told ITV Daybreak that "these reforms start putting customers first again.
"The really key thing here is to help customers get on the best tariff for their circumstances."
We welcome today's announcement. Everyone wants a simpler more trusted market. There is a lot in this reform package that could bring that closer. Now Ofgem needs to get on and implement it and energy companies need to respond to the spirit of the reforms.
But it would be naive to assume that this will sort out the energy market once and for all. The market needs to earn consumer confidence. There are also areas where Ofgem needs to go further, which include making it much easier for customers to switch supplier.
There are still some crinkles in the reforms to be ironed out. However, Ofgem has delivered a strong set of reforms and now it is up to the industry to start to deliver.
The proof of this pudding will be in the eating though and we will all know that Ofgem has succeeded when growing numbers of households are able to use competition to get better value and cheaper energy bills.
- Ofgem have told suppliers to limit themselves to four "core" tariffs each for electricity and gas and for each type of payment.
- All information suppliers send to consumers must be "simplified, more engaging and personalised".
- Suppliers will use a new Tariff Comparison Rate (TCR), which the regulator claims will help to simplify the selection process for consumers.
- And new enforceable standards of conduct will enable Ofgem to take action against suppliers where they have failed to treat customers fairly.