Shockwaves reverberated through Eastern Europe tonight after Vladimir Putin boasted he could invade five NATO capitals inside two days.

This came amid new reports that almost 4,000 Russia troops are massing in Crimea close to Ukraine's mainland.

'If I wanted, Russian troops could not only be in Kiev in two days, but in Riga, Vilnius, Tallinn, Warsaw or Bucharest, too,' Putin was quoted as threatening, according to Ukrainian president Petro Poroshenko.

All are former USSR or Soviet-bloc cities and apart from Ukraine their countries are now NATO and EU members.

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Putin, pictured here at a meeting of the Russian State Council, boasted Russia could be in Kiev in two days - and also in Riga, Vilnius, Tallinn, Warsaw and Bucarest

Putin allegedly also boasted to Poroshenko about his ability to squash European Union initiatives through bilateral contacts urging him 'not to rely too much on the EU'.

The Kremlin leader claimed he could 'influence and block the adoption of decisions at the level of the European Council', it was alleged.

Respected German newspaper Suddeutsche Zeitung reported that Poroshenko passed on the threat of invasion to European Commission President Jose Manuel Barroso, citing EU diplomatic sources.

Poroshenko warned the US Congress of a threat to 'global security everywhere' posed by the Russian aggression against his nation.

'If they are not stopped now, they will cross European borders and spread throughout the globe,' he said.

The EU failed to deny the extraordinary threat from Putin, though the Kremlin dismissed the German newspaper report.

'We will not conduct diplomacy in the media or discuss extracts of what are confidential conversations,' said EU Commission spokeswoman Pia Ahrenkilde Hansen sidestepping the question. 'What matters to the EU is to contribute to lasting peace, prosperity and stability in Ukraine.'

Putin's spokesman Dmitry Peskov dismissed the claim as 'another canard', alleging was as inaccurate as an earlier claim that Putin had boasted he could storm Kiev in two weeks.

'We consider it possible not to pay attention to such reports anymore,' he said.

However, Kiev claimed that Russia was massing troops in annexed Crimea, just as Poroshenko was meeting Barack Obama in Washington.

Poroshenko, pictured here in Washington today, passed on the threat of invasion to European Commission President Jose Manuel Barroso, citing EU sources

NATO leaders have backed Ukraine claiming that a new rapid-reaction 'spearhead' force could be deployed within a year.

The force, which will have 4,000 to 5,000 troops on standby is designed to be deployed in the field within three days.

NATO leaders believe a strong western response will curtail Vladimir Putin's expansion plans.

The NATO move is in response to Ukrainian requests for more assistance from western powers to curtail Putin.

Mr Poroshenko's accusations came as a rocket shelling appeared to take place near the front line in Zuivka, some 30 miles east of Donetsk

Ukrainian President Petro Poroshenko said: ' Please understand me correctly. Blankets, night-vision goggles are also important. But one cannot win the war with blankets. Even more, we cannot keep the peace with a blanket.'

Mr Poroshenko welcomed the defensive equipment pledged by the US but called on the west to supply Ukraine with offensive weapons.

Almost all Russian military units 'in the north of occupied Crimea' were pushed close to mainland Ukraine 'along with all their equipment and ammunition', said National Security and Defence Council spokesman Andriy Lysenko.

Despite Kremlin denials, the alleged Putin claim created a wave of angst across eastern Europe.

Estonian foreign minister Urmas Paet warned in the wake of Putin's comments: 'We shouldn't let the public stress level rise all the time since it's not helping anybody.'

More shelling in Zuivka: Kiev claimed that Russia was massing troops in annexed Crimea even as Poroshenko was meeting U.S. leaders in Washington

He added: 'It is clear that the security situation in Europe has changed due to the events in Ukraine.'

Lithuania announced a weekend meeting of NATO top brass in Vilnius amid high anxiety over Russia's actions in Ukraine.

'For us, it is important that the NATO military chiefs discuss how to strengthen the security of the Baltic region,' said Defence Minister Juozas Olekas.

Poroshenko said his country was now angled to the West .

'Ukraine crossed the Rubicon and ruined any hopes to restore the Soviet Union. We are a European nation,' he said.