* Rouble briefly slips past 75 vs dollar, 85 vs euro

* Rouble at lowest levels since late November

* Rouble ends 2021 near level of late 2020

* Putin-Biden phone call in focus

MOSCOW, Dec 30 (Reuters) - The rouble hit a one-month low in thin and volatile trade on Thursday ahead of a phone call between President Vladimir Putin and his U.S. counterpart Joe Biden at a time of strained Moscow-Washington relations over Ukraine.

By 1728 GMT, the rouble was 1.1% lower against the dollar at 74.80 after hitting 75.15, its weakest since Nov. 30.

It was down 0.9% at 84.64 against the euro, having earlier touched 85.1750, also a one-month low.

The rouble ends 2021 0.5% stronger against the dollar than a year earlier after hovering within a range of 69.21-78.05 during the year.

Selling pressure on the rouble increased on the last trading day of 2021 as Moscow Exchange will be closed on Friday. Russia's largest bourse will reopen on Monday but trading activity is not expected to recover to regular levels until Jan. 10, the end of Russia's New Year holidays.

The rouble has been under increased pressure since October as Western nations have expressed concerns about Russia's military build-up near neighbouring Ukraine. Moscow says it can move its army around its own territory as it deems necessary.

Putin and Biden will speak at 2030 GMT as Washington crafts a common response with European allies to Russia's military moves. Russia denies planning to attack Ukraine.

In the longer run, the rouble is set to receive support from the central bank that is expected to continue raising rates as consumer inflation, its main area of responsibility, remains high.

VTB Capital said the rouble will average 72.30 versus the dollar in January and 71.80 in March, assuming a stable foreign share in Russian OFZ government bonds, oil prices near $80 per barrel, and no increase of the emerging markets external risk premium.

Brent crude oil, a global benchmark for Russia's main export, was down 0.1% at $79.14 a barrel but Russian stock indexes were up.

The dollar-denominated RTS index rose 0.4% to 1,595.8 points, while the rouble-based MOEX Russian index added 1.2% to 3,787.3 points. (Reporting by Alexander Marrow and Andrey Ostroukh; Editing by Vinay Dwivedi, Emelia Sithole-Matarise and Alison Williams)