Moscow was plunged into chaos yesterday by a power failure that President Vladimir Putin blamed on the state-owned electricity monopoly headed by a liberal politician viewed with suspicion by the Kremlin.

The outage shut the stock exchange, crippled transport and threatened mobile phone links in the sweltering Russian capital.

Energy Minister Viktor Khristenko said it was caused by a fire and explosion overnight at an electricity substation. There was no evidence of a terrorist attack, he said.

But Mr Putin, who delayed a provincial trip because of the crisis, pointed the finger at the management of Unified Energy System headed by Anatoly Chubais, one of the architects of the post-Soviet market revolution whose liberal views sit uneasily with Kremlin hardliners.

Mr Chubais, one of Russia's best known figures who survived an assassination attempt in March, was quoted as saying he accepted full responsibility for the outage.

Russian prosecutors opened a criminal case against the management of RAO UES, Interfax news agency reported.

The case was opened to investigate possible negligence.

Mr Putin was clearly suggesting that Mr Chubais was spending too much time on his widely-publicised plans for a corporate restructuring of the electricity behemoth and was losing sight of the operational running of the firm.

Moscow's main MICEX foreign exchange and share market stopped trading for several hours because, though it had power, many of its clients did not. It reopened later in the afternoon.

The underground system ground to a halt, leaving more than 20,000 passengers stranded below ground during a heatwave with temperatures soaring to 30°C.