MOSCOW, Oct 30 (Reuters) - The Russian rouble weakened against the U.S. dollar and China's yuan on Thursday after Russian exporting companies had completed foreign currency sales to make their tax payments at the end of the month.

By 1000 GMT, the rouble RUB= was down 0.5% at 80.40 against the dollar in over-the-counter trade, and by 0.8% at 11.30 against the yuan on the Moscow Stock Exchange, where the Chinese unit is the most traded foreign currency.

"In the short term, the rouble's exchange rate will be determined by the exporters' demand for Russian currency and the extent of their willingness to invest in deposits and bonds," Alor brokerage analysts said.

Most analysts see the rouble as overvalued, predicting it will weaken towards the end of the year. The central bank says a growing number of restrictions on Russia's ability to import goods is contributing to the rouble's strength.

(Reporting by Gleb Bryanski, editing by Ed Osmond)

((gleb.bryanski@thomsonreuters.com;))