UPDATE 1-Argentine central bank sells $500 mln to lift peso

(Updates with analyst comment, regional context)

BUENOS AIRES, Oct 10 (Reuters) - Argentina's central bank on Friday sold more than $500 million worth of dollars to support the local currency, foreign exchange traders told Reuters, mirroring similar actions elsewhere in the region.

This would be three to four times the amount the central bank normally uses to buoy demand for the peso during periods of market turbulence, according to traders.

Central bank officials would not comment on the reports.

"The central bank was very active in the session from the start ... selling $539 million at different prices," said Jose Nogueira, an analyst at ABC Mercado de Cambios.

In formal trade between banks ARS=RASL, where the central bank intervenes, the peso closed 0.31 percent firmer at 3.22/3.2225 per dollar, after slumping to 3.2725/3.2750 earlier in the session.

In informal trade between foreign exchange houses, as measured by Reuters, the peso closed down 1.2 percent at 3.36/3.37 per U.S. dollar ARSB=, after trading as weak as 3.40/3.45 just after the market opened.

The peso is at its weakest levels since a currency devaluation in 2002.

Mexico's central bank sold $8.9 billion this week to prop up its battered peso currency MXN= MEX01, or a little more than one-tenth of its foreign reserves.

The Brazilian central bank also intervened this week to stem steep losses in the real (BRBY).

Argentina's central bank has acted to stabilize the local peso since 2003. It used to buy dollars on the foreign exchange market to keep the peso weak for exports, but in recent months it has had to sell its dollar reserves to keep the peso from weakening too much. (Reporting by Jorge Otaola and Walter Bianchi; Writing by Hilary Burke; Editing by Diane Craft)