MOSCOW, May 23 (Reuters) - The Russian rouble slightly

weakened against the U.S. dollar on Thursday.

By 0715 GMT, the rouble was 0.29% lower at

90.32 to the dollar after trading in a range of 89.970 to

90.368.

Against the euro, the rouble fell 0.01% to

97.80 and dropped 0.17% to 12.43 against the yuan

.

Brent crude oil, a global benchmark for Russia's

main export, fell 0.3% to $81.64 a barrel.

Russian stock indexes fell. The dollar-denominated RTS index

fell 0.87% to 1,193.09. The rouble-based MOEX Russian

index lost 0.7% to 3,420.84.

($1 = 90.3200 roubles)

(Reporting by Reuters)