The Russian rouble edged lower against the dollar on Thursday, struggling to pull away from the 100 threshold, as authorities discussed a range of capital control measures that could be implemented to prop up the currency.

At 0802 GMT, the rouble was 0.2% weaker against the dollar at 96.32 and had gained 0.3% to trade at 102.67 versus the euro. It was steady against the yuan at 13.16.

The Bank of Russia jacked up the cost of borrowing at a third meeting in succession last week in response to the weak rouble, which tumbled to a near 17-month low of 101.75 to the dollar in August.

Rate increases appear to have had a limited effect so far, but the Bank of Russia's Deputy Governor Alexei Zabotkin disputed that.

"If the rate had remained at 8.5%, then we would now be looking at a different level of the exchange rate, which would likely be well into triple digits," Interfax quoted Zabotkin as saying on Wednesday. "In that sense, from the viewpoint of the current exchange rate, the key rate has had an impact."

Authorities are discussing reintroducing currency control measures to support the rouble. The central bank is largely opposed while the government is more in favour of action.

Deputy Finance Minister Alexei Moiseev said on Wednesday a series of measures was being developed and discussed, aimed primarily at reducing capital outflows through countries that Russia considers friendly - that is, those that have not imposed sanctions over Moscow's invasion of Ukraine.

Moiseev said Russia was partly a "hostage" to its own policy of promoting the use of roubles in international settlements.

"Unfortunately, in a situation when outflow through unfriendly countries in unfriendly currencies is significantly hampered, the outflow of capital through friendly countries, and moreover in roubles... leads to (the withdrawal of capital through friendly countries)," Interfax quoted Moiseev as saying.

Brent crude oil, a global benchmark for Russia's main export, was down 0.9% at $92.66 a barrel.

Russian stock indexes were lower.

The dollar-denominated RTS index was down 0.9% to 993.3 points. The rouble-based MOEX Russian index was 1% lower at 3,038.4 points. (Reporting by Alexander Marrow Editing by Gareth Jones)