Moldova's pro-EU leaders have rejected Russian claims that Ukraine is planning to attack the country's breakaway pro-Russian territory, and called for calm.

Russia's defence ministry alleged, with no evidence, that Ukrainian saboteurs would stage an invasion of Transnistria dressed as Russian soldiers as a pretext for a Ukrainian invasion.

Moldova has warned for weeks that Russia is plotting to seize power.

And officials rejected Russia's claims as "psy-ops" as part of the war.

Moldovan President Maia Sandu, on a visit to neighbouring Romania, spoke of unprecedented security challenges ahead.

"Some wanted our country to fall and to install in Chisinau a puppet government enslaved to the interests of the Kremlin," she said.

Moldova is not part of Nato but last June it was awarded EU candidate status on the same day as Ukraine. Earlier this week the Moldovan leader met US President Joe Biden, who promised to support her country's sovereignty.

With a population of just 2.6 million, Moldova is one of Europe's poorest economies and has been heavily exposed to the war in Ukraine.

It has faced a major energy crisis because its power infrastructure dates back to the Soviet era. Not only did Russia restrict its gas supplies but its attacks on Ukraine's power grid had knock-on effects.

Rampant inflation and a big influx of refugees from Ukraine have created further pressures, leading to protests organised by the populist and pro-Russian Sor party, led by fugitive oligarch Ilan Shor.

There has also been an apparent escalation of incidents described by new Prime Minister Dorin Recean as "hybrid attacks".

A Russian missile was fired at Ukraine through Moldovan airspace on the day the previous government collapsed earlier this month, in the face of what his predecessor called "multiple crises".

President Sandu has accused Russia of plotting to bring down Moldova's leadership with the aid of foreign saboteurs from Russia, Serbia, Belarus and Montenegro. She said their aim would be to attack government buildings, seize hostages and then spark protests to replace the government with one "at the service of Russia".

Shortly after her speech, twelve Serbian football fans were barred from entering Chisinau for a match.

The Kremlin accused Moldova's leaders of slipping into anti-Russian hysteria and warned them to be "very, very careful" with their statements.

Political analyst Denis Cenusa said Moldova's weakest point for pro-Russian forces was its internal socio-economic stability. If Russia failed in the short term, he said it could succeed at the ballot box in local elections this year and the presidential vote in 2024.

On Moldova's eastern flank lies a narrow strip of land called Transnistria, between the Dniester river and the Ukrainian border. Dominated by Russian speakers, it proclaimed independence from Moldova in 1990 as the Soviet Union fell apart.

A short border war led to a ceasefire in 1992 and that has been enforced ever since by 1,500 Russian troops stationed there.

As soon as Russian forces invaded southern Ukraine a year ago there were fears they would try to seize Odesa and the entire coast to Transnistria.

That has not happened, but what Moldova's leaders are warning of now is reminiscent of what happened in April 2022.

A series of mysterious explosions were reported, which separatist authorities in Transnistria said targeted their state security HQ, old Soviet-era radio masts and a military unit.

Ukrainian "infiltrators" were held responsible then as well by Transnistria's authorities. Kyiv blamed Russian special services, warning they were seeking to threaten Moldova and destabilise the situation.

Earlier this week a pro-separatist social media channel said it had seen Ukrainian military equipment on the motorway linking Ukraine to Moldova, but an unconvincing photo showed only a couple of small armoured vehicles and a Ukrainian flag.

The head of Transnistria's peacekeeping body, Oleg Belyakov, said there was no panic among its population but Russia's warnings did "give reasons for serious concerns".