NATO should redeploy its forces in eastern Europe and take a firm stand to prevent a contagion of the Ukraine crisis, Romania's foreign minister urged in an interview Thursday with AFP.

"Romania has concrete expectations of a redeployment and an eastward repositioning of NATO's naval, air and ground forces," Titus Corlatean said.

"The Black Sea region must be a top priority for NATO and the EU," he stressed.

Bucharest "is extremely concerned over developments in Ukraine which have a serious impact on international security," Corlatean said, stressing his country is "on the frontline".

Romania, a member of both the European Union and the North Atlantic Treaty Organisation, shares a border with Ukraine in the east and in the north.

The US charg� d'affaire in Romania, Duane Butcher, told Mediafax news agency that the US is currently thinking about "a wide range of measures" to consolidate trust among its allies.

"We will defend Romania", he insisted.

The United States has already sent six F-15 fighter-bombers, a dozen F-16 fighter jets and three transport aircraft to Poland. A US guided missile destroyer is also due in the Black Sea in the coming days.

- Nato should stand firm -

In recent days pro-Kremlin activists have seized government buildings in several cities in Ukraine's east, declaring independence and vowing to vote on splitting from Ukraine.

The US has accused Moscow of trying to "create chaos" to justify military intervention like in Crimea.

"Our expectations towards Russia are clear and firm: it should engage in a political dialogue and avoid escalation," the Romanian minister of Foreign Affairs stressed.

EU and NATO should "stand firm in order to stop potential risks of contagion of the crisis from Odessa in Southern Ukraine to Transdniestr", a pro-Russian breakaway region in Moldova.

Trasndniestr, a strip of land on Moldova's eastern border, broke away from the rest of the country in the wake of the 1991 fall of the Soviet Union but is not recognised by any other state.

On Monday, its leader, Yevgeny Shevchuk, said his dream would be to see the region "together with Russia".

Moscow maintains thousands of troops there against the will of the pro-Western Moldovan government.

"We hope that a political dialogue will prevail", Corlatean insisted, saying Russia could show its good will by participating in a new round of negotiations planned next week to solve the Transdniestr situation.

"It is important that these talks take place even if they are delayed because this will show if Moscow is more open on the matter or not.

"We have no interest in a clash between the European Union and Russia", but Corlatean warned that if Moscow choses escalation, "further sanctions are still an option".

And the gas issue should not be a reason to "forget about the fundamental values of international law".

Russian Gazprom provides about a third of all gas consumed by EU nations and is the sole provider of energy for some central European states such as Slovakia.

"There is a lot of talk about Europe's dependence on Russian gas but Russia is also depending on European markets" to sell its production, Corlatean said.

"Russia could have an interest in listening to what Europe wants on Ukraine", he says.

President Vladimir Putin on Thursday sent a letter to leaders of 18 European countries, warning them Russia could cut gas supplies to Ukraine.