Dec 31 (Reuters) - Russian gas supplies sent via Ukraine

to Europe for more than 40 years are scheduled to end on January

1 after Ukraine's Naftogaz refused to renew its latest five-year

transit deal with Russia's Gazprom.

Despite the war between the two countries, Ukrainian

President Volodymyr Zelenskiy on Dec 19 said Kyiv might consider

allowing the transit of Russian gas if payments to Moscow were

withheld until the fighting ends.

Russian President Vladimir Putin a week later said there was

no time left this year to sign a new deal.

Here is what we know about options for when Russian gas

transit via Ukraine stops.

HOW BIG ARE THE VOLUMES?

Russia's supply to Europe has fallen dramatically in the

wake of Moscow's invasion of Ukraine in Feb. 2022 which spurred

the European Union to cut its dependence on Russian gas.

Moscow spent half a century building its European gas market

share, which at its peak stood at about 35% but has fallen to

about 8%.

As of Dec. 1 the EU received less than 14 billion cubic

metres (bcm) of gas from Russia via Ukraine, down from 65

bcm/year when the latest five-year contract began in 2020.

The European Commission has said that volume can be fully

replaced by liquefied natural gas and non-Russian pipeline

imports.

Moscow has lost market share to rivals such as Norway, the

United States and Qatar.

Russia could earn around $5 billion on sales via Ukraine

this year based on an average Russian government gas price

forecast of $339 per 1,000 cubic metres, Reuters calculations

show.

Ukraine earns between $800 million and $1 billion in

transit fees per year.

EU gas prices rallied in 2022 to record highs after the loss

of Russian supplies. With supplies set to end, EU officials and

traders say a repeat of that rally is unlikely given the now

modest volumes involved and the small number of customers

remaining.

WHO IS AFFECTED?

The Ukraine route serves Austria and Slovakia.

Austria received most of its gas via Ukraine, while Slovakia

takes around 3 bcm from Gazprom per year, about two-thirds of

its needs.

Gazprom halted supply to Austria's OMV in

mid-November over a contractual dispute but volumes held steady

via the route as other buyers stepped in.

Slovakia has said the loss of Russian supply would not

hit its consumption and that it has diversified supply

contracts. Its main gas buyer SPP has contracts for non-Russian

supply with BP, Eni, ExxonMobil ( XOM ), RWE

and Shell.

WHAT OPTIONS DO BUYERS HAVE?

Most other Russian gas routes to Europe are shut including

Yamal-Europe via Belarus and Nord Stream under the Baltic Sea.

One option is the TurkStream pipeline to Turkey under the

Black Sea, Bulgaria, Serbia or Hungary. However, capacity is

limited.

Slovakia's gas supply could come from Hungary, roughly a

third from Austria and the remainder from the Czech Republic and

Poland, according to Austrian energy regulator E-Control.

Austria should not face disruptions as it has prepared

for the switch in supply, its regulator has said.

The Czech Republic is likely to tap more supply from Germany

pipelines taking advantage of an exemption from a German

domestic gas levy from Jan. 1.

The Czech Republic has said it is ready to provide Slovakia

with gas transit and storage capacities.

Russia supplies Moldova with about 2 bcm of gas per year. It

is piped via Ukraine to the breakaway region of Transdniestria

where it is used to generate cheap power that is sold to

government-controlled parts of Moldova.

Gazprom said it plans to suspend supply on Jan. 1 citing

unpaid bills.

Moldovan Prime Minister Dorin Recean has condemned the

decision but said the country has diversified sources of supply.

The country plans measures to reduce consumption by at least a

third from Jan. 1.

As for Ukraine, its security of supply will not be impacted

as it does not use Russian transit gas, the European Commission

said.

WHERE DOES THE GAS COME FROM?

The Soviet-era Urengoy-Pomary-Uzhgorod pipeline carries gas

from Siberia via the town of Sudzha - which is now under control

of Ukrainian military forces - in Russia's Kursk region.

It flows through Ukraine to Slovakia where the pipeline

splits into branches going to the Czech Republic and Austria.

Transdniestria borders Ukraine and also receives Russian

gas via Ukraine.