May 28 (Reuters) - The Russian rouble strengthened

beyond the 80 mark to the dollar on Wednesday, pulling back from

a one-week low it hit in early trade, with market players

keeping an eye on geopolitical developments.

The United States and Russia quarrelled in public on

Wednesday over the intensifying war in Ukraine as U.S. President

Donald Trump warned that his counterpart Vladimir Putin was

"playing with fire" and Moscow massed 50,000 troops near a

Ukrainian region.

By 0813 GMT, the rouble was up 0.6% at 79.75 per U.S.

dollar, LSEG data based on over-the-counter quotes showed. The

Russian currency hit a one-week low of 80.50 earlier in the

session.

The rouble has strengthened by over 40% against the dollar

this year, a rise analysts have attributed to the easing of

geopolitical tensions - mainly with Trump's administration - and

the central bank's tight monetary policy, which has reduced

demand for foreign currency.

Russia's government last week said it had extended

requirements for major exporters to sell a proportion of their

foreign currency earnings until the end of April 2026,

buttressing the rouble.

Those restrictions, the Bank of Russia's 21% key interest

rate and month-end tax payments, which usually see exporters

convert their foreign currency earnings into roubles to pay

local liabilities, are all supporting the rouble.

Against the Chinese yuan, the rouble was up 0.4% at 11.06 on

the Moscow Stock Exchange. Russia's central bank uses yuan for

foreign exchange interventions, and it is the most-traded

foreign currency in Russia.

The rouble is set to lose tax payments support from

tomorrow, said Bogdan Zvarich of Promsvyazbank, which will

likely prevent it from strengthening past 11 to the yuan, while

continued geopolitical uncertainty and low oil prices could see

it start to weaken.

Brent crude oil, a global benchmark for Russia's

main export, was up 0.5% at $64.42 a barrel.