MOSCOW, Jan 25 (Reuters) - The rouble pared gains to weaken on Tuesday heading back towards a more than 14-month low versus the dollar after a massive sell-off in the previous session, with Russian assets highly sensitive to tensions between Moscow and the West over Ukraine.

Volatility has plagued Russian markets in recent weeks amid Western fears Russia is poised to invade its neighbour, something Moscow has repeatedly denied. The West has threatened sanctions https://www.reuters.com/markets/europe/how-financial-western-sanctions-might-target-russia-2022-01-19 with profound economic effects if Russia does make an incursion.

NATO said on Monday it was putting forces on standby and reinforcing eastern Europe with more ships and fighter jets, in what Russia denounced as Western "hysteria" in response to its build-up of troops on the Ukraine border.

By 1400 GMT, the rouble was 0.3% weaker against the dollar at 79.01, paring earlier gains. On Monday it fell to 79.50, the rouble's weakest point since Nov. 3, 2020.

Versus the euro, the rouble gained 0.1% to trade at 89.01 , recovering from its weakest since July 2021, hit on Monday.

"A corrective bounce is not off the cards considering the scale of yesterday's sell-off, however U.S.-Russia tensions remain as hot as they ever have been and the trend would suggest further weakness ahead," said BCS Global Markets in a note.

The rouble benefited briefly from Russia's central bank saying it would stop foreign currency purchases on Monday before losses resumed. That action probably stopped the rouble from weakening past 80 against the greenback, said Dmitry Polevoy, head of investment at Locko Invest.

Under a fiscal rule adopted in 2017 to strengthen the National Wealth Fund, Russia buys foreign currency when oil prices are high and sells when prices go below $44 per barrel, shielding the rouble from oil price swings.

Brent crude oil, a global benchmark for Russia's main export, was up 0.7% at $86.87 a barrel.

For a second straight week, the finance ministry cancelled weekly auctions of OFZ treasury bonds due on Wednesday, in an effort to facilitate market stabilisation, citing persistent volatility on financial markets.

Russia's 10-year OFZ bond yields eased to 9.70%, down from 9.77% hit earlier on Tuesday, which was their highest since early 2016. Yields move inversely to prices.

Russian stock indexes were recovering after sinking to their lowest since late 2020 in the previous session.

The dollar-denominated RTS index was up 1.2% to 1,303.6 points. The rouble-based MOEX Russian index was 1.1% higher at 3,269.3 points.

(Reporting by Alexander Marrow, Additional reporting by Gabrielle Tétrault-Farber and Katya Golubkova, Editing by Mark Potter, Peter Graff and Ed Osmond)