April 19 (Reuters) - The Russian rouble edged lower against the dollar on Wednesday, waiting for the impact of a favourable month-end tax period to help strengthen it and ahead of two OFZ treasury bond auctions by the finance ministry.
At 0801 GMT, the rouble was 0.2% weaker against the dollar at 81.58 and unchanged at 89.39 versus the euro . It had firmed 0.3% against the yuan to 11.81 .
The rouble is expected to gain support from month-end tax payments that usually lead exporters to convert foreign currency revenues to meet local liabilities. Those taxes are due on April 28 and so far the influence of this factor on the rouble is limited, said Bank St Petersburg analysts in a note.
"Against this backdrop, the dollar-rouble rate is likely to stay above 81 with the potential to move below this level at the start of next week."
The Russian currency should also get a delayed boost from this month's higher oil prices, which translate to higher export revenues.
Brent crude oil, a global benchmark for Russia's main export, was down 1.2% at $83.8 a barrel on Tuesday, but still well above levels seen in late March below $80 per barrel.
Russian stock indexes were higher.
The dollar-denominated RTS index was up 0.4% to 1,014.4 points. The rouble-based MOEX Russian index was 0.5% higher at 2,627.8 points, renewing a more than one-year high.
"An impression is developing that investors are using any reason to activate purchases, completely ignoring the fact that the market is overbought," said Alor Broker's Alexei Antonov.
He said rumours about a second wave of mobilisation had failed to bring the market down and that optimistic forecasts of economic growth this year were supporting Russian stocks.
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For Russian treasury bonds see (Reporting by Alexander Marrow Editing by Peter Graff)
