UPDATE 2-Argentina says scraps some mining export tax breaks

(Adds details, Xstrata comment)

By Helen Popper

BUENOS AIRES, Dec 5 (Reuters) - Argentine authorities said on Wednesday they had scrapped tax exemptions for mining companies, meaning some now face export duties of 5 percent or 10 percent.

It was not immediately clear which projects would be subject to the higher taxes, but the Argentine mining chamber (CAEM) said four companies had already been asked for the new payment on Tuesday.

"The Mining Secretariat has rolled back the authorizations that some mining companies and projects had benefited from," customs director Ricardo Echegaray said in a statement. "The tax exemption is no longer in effect."

No one at the Mining Secretariat or customs could immediately be reached to give further details.

Major mines in Argentina include the primary copper mine Alumbrera that is 50-percent owned by Swiss-based Xstrata Plc (XTA.L), Barrick Gold Corp's (ABX.TO) Veladero, and the Cerro Vanguardia gold mine, run by AngloGold Ashanti (ANGJ.J).

In a statement on Tuesday, the mining chamber said four firms had been asked to make the extra payment, including Minera Alumbrera Ltd.

However, Xstrata spokeswoman Emily Russell said: "No requests have been made to Alumbrera."