Sept 29 (Reuters) - The Russian rouble weakened to a more than two-week low against the dollar on Friday, heading back past the 97 mark as a favourable month-end tax period passed.

At 0800 GMT, the rouble was 0.5% weaker against the dollar at 97.32, its weakest point since Sept. 14.

It lost 0.9% to trade at 103.12 versus the euro and shed 0.2% against the yuan to 13.33 .

The rouble tumbled past 100 to the dollar last month, leading authorities to discuss the possibility of reintroducing controls to buttress the currency.

Month-end tax payments, that usually see exporters convert foreign currency revenues to pay local liabilities, support the rouble, but the currency can slide once the period has passed.

The rouble has also now lost the temporary support of higher sales of foreign currency than usual by the central bank, which was selling around 21.4 billion roubles ($220.6 million) of yuan a day until the start of this week.

The rouble fared better than expected after the tax period passed this week, said Alor Broker's Alexei Antonov, but the currency is not out of the woods yet.

"It's possible that the market started receiving an increased inflow of export revenues from oil firms due to the growth in oil prices in recent months," Antonov said. "But this does not for now override the scenario of the dollar-rouble pair going to the region of 100."

Brent crude oil, a global benchmark for Russia's main export, was down 0.3% at $95.08 a barrel. It hit a 10-1/2 month high in the previous session.

Russian stock indexes were mixed.

The dollar-denominated RTS index was steady at 1,011.1 points, while the rouble-based MOEX Russian index was 0.5% higher at 3,124.6 points.

Shares in steel pipemaker TMK were 1.8% higher, outperforming the wider market, after the company said it had raised 4 billion roubles in a secondary public offering.

($1 = 97.0025 roubles) (Reporting by Alexander Marrow; Editing by David Holmes)