CHISINAU (Reuters) -Moldova's state energy firm will pay the rest of a late advance payment to Russia's Gazprom for September natural gas supplies on Friday so the gas giant does not cut supplies from Oct. 1, a source said on Thursday.

Moldovagaz paid $6 million to Gazprom on Thursday and will pay more than $24 million on Friday to close the late advance payment of $33.89 million that was due to be paid by Sept. 20 to cover 50% of gas consumed in September, the source told Reuters.

The remaining 50% is due to be paid for by Nov. 20.

One of Europe's poorest countries, Moldova is reliant on Russian gas, the price of which has surged this year because the contract with Gazprom fluctuates from month to month based on the spot price of gas and oil.

From October, the price Moldova pays is set to tumble from $1,882 per thousand cubic metres to $1,060 because the pricing formula is no longer linked so strongly to the spot price of gas, the source said.

High energy prices are a politically sensitive matter.

Thousands of protesters have gathered in Chisinau over the last two weekends, demanding the resignation of President Maia Sandu and her government and complaining of high inflation and fuel prices.

(Reporting by Alexander Tanas; writing by Tom Balmforth; editing by David Evans and Cynthia Osterman)