KYIV, Jan 4 (Reuters) - Power cuts will continue on Saturday in the breakaway Moldovan region of Transdniestria, which has been left without Russian gas supplies following Ukraine's decision not to extend a contract for Russian gas transit, local authorities said.

Flows of Russian gas via Ukraine to central and eastern Europe were halted on New Year's Day after the expiry of a transit agreement between the warring countries, and Kyiv rejected doing further business with Moscow.

Transdniestrian officials said the first rolling power cuts had gone into effect on Friday evening.

The mainly Russian-speaking region, which lies along the Moldova-Ukraine border and which split from Moldova in the 1990s, had been receiving Russian gas via Ukraine and used it to produce electricity.

The official Telegram news channel of Transdniestria's government said power supplies would be cut for three hours between 2 p.m. (1200 GMT) and 5 p.m. in many districts.

The enclave's self-styled president Vadim Krasnoselsky had earlier said power cuts were inevitable. He said the region had gas reserves to cover 10 days of limited usage in the north and twice as long in the south. He did not say if there were any plans to source supplies after that.

On Saturday, Krasnoselsky said on Telegram that the blackouts could be extended to four hours on Sunday.

Russia denies using gas as a weapon to coerce Moldova, and blames Kyiv for refusing to renew the gas transit deal.

Moldova itself gets around 60% of its gas needs from Romania and produces the rest. But the Transdniestria power cuts are a problem for Moldova particularly because the enclave is home to a power plant which provides most of the power for government-controlled areas of Moldova at a fixed and low price.

Prime Minister Dorin Recean said on Friday his country faced a security crisis after Transdniestria's imposition of rolling blackouts, but he also said the Chisinau government had prepared alternative arrangements, with a mixture of domestic production and electricity imports from Romania.

Moldova says Russian gas major Gazprom could supply gas bypassing Ukraine but has deliberately chosen not to do so. Even before the halt of supplies via Ukraine, Gazprom had said on Dec. 28 that it would suspend exports to Moldova on Jan. 1 because of what Russia says are unpaid Moldovan debts of $709 million.

Moldova disputes that and put the figure at $8.6 million.

(Reporting by Pavel Polityuk; Editing by David Holmes)

((pavel.polityuk@tr.com; +380 44 2449150))