(Adds oil price, c.bank currency interventions)
* Russia allows fourth rouble devaluation in a month
* C.bank spent estimated $10 bln on FX intervention this wk
* Weakening oil price adds to pressure on currency
By Yelena Fabrichnaya and Gleb Bryanski
MOSCOW, Dec 5 (Reuters) - Russia's central bank devalued the rouble for a fourth time within a month on Friday as the price for Urals, Russia's main export blend of oil, fell below $38 per barrel, its lowest since February 2005.
The rouble weakened by one percent to 31.62 in early trade against the basket of 0.55 dollars and 0.45 euros, which the regulator uses to guide its exchange rate policy.
The move also came one day after Russia's gold and foreign exchange reserves posted their first weekly rise in two months, enabling Prime Minister Vladimir Putin to say the cash will help the economy weather the global crisis.
The central bank runs a managed float of the rouble, keeping it within a band against the basket. Given low oil prices and persistent capital outflows, the rouble will tend to weaken after a band widening.
"The current account surplus, which will likely disappear in the current quarter, no longer supports the current rouble exchange rate," said ING analyst Tatiana Orlova.
A source in the central bank confirmed the trading band had been widened further. The central bank was forced to let the rouble depreciate in three one-percent steps against a euro-dollar basket last month.
The central bank said it had spent $57.5 billion in Sept-Oct to rebuff an attack on the rouble. Dealers said the regulator had sold about $10 billion this week but noted that the speculative pressure on the rouble was easing.
"People are getting used to the gradual devaluation. Market panic and unhealthy demand are receding. Today it is not as interesting to buy dollars as it was when the basket was at 30.40," said OTP bank's trader Anton Murashov.
The rouble closed at 31.62 against the basket on Friday.
SCEPTICAL
Economists polled by Reuters last month expected the rouble to weaken further against the basket to 33.44 by the end of 2009. The rouble is down by 20 percent from its July peak against the dollar, reflecting the dollar surge internationally.
The central bank declined to comment on the latest move officially. Economists, meanwhile, are split over what the central bank should do.
Troika Dialog analyst Evgeny Gavrilenkov said a large one-time devaluation would be a useful step towards the rouble's float, proclaimed by the central bank as a medium-term target, and a weaker currency would help industry. Others disagreed.
"We are sceptical about the possibility of bigger rouble devaluation as it would fuel inflation, and potentially lead to rising social tensions," said ING's Orlova.
Russian households closely watch the dollar exchange rate. With the central bank data showing an "unprecedented" $10.3 billion in net demand for foreign currency in October, confidence in the government's anti-crisis measures is at stake.
The government is also facing a problem channelling the money it pumps into the banking sector to enterprises, with spreads between official and market interest rates at over 10 full percentage points.
The central bank has accompanied some of its devaluation moves with rate hikes, gradually moving official interest rates in real terms out of the negative territory where they have been in recent years. Some analysts also questioned the logic behind the central bank's move one day after the increase in reserves.
"The situation becomes more unclear. Certainly not an environment to attract foreign capital," said Ulrich Leuchtmann from Commerzbank. (Additional reporting by Andrei Ostroukh, Toni Vorobyova, Dmitry Zhdannikov; Reporting by Yelena Fabrichnaya, writing by Gleb Bryanski; Editing by Ruth Pitchford and Andy Bruce)