Polandxe2x80x99s prime minister has accused Vladimir Putin of xe2x80x9cmastermindingxe2x80x9d the migrant crisis on Belarusxe2x80x99s border with the EU, while Minskxe2x80x99s key ally in the Kremlin pointed the blame at Europe.

The escalating rhetoric, including claims from the Belarusian leader, Alexander Lukashenko, that Russia could join a potential conflict at the border, has underlined the role that regional alliances are playing in the standoff and ensuing humanitarian crisis.

Poland and Lithuania have declared a state of emergency on their borders with Belarus, where Lukashenko has been accused of ferrying asylum-seekers from the Middle East to the EUxe2x80x99s borders as revenge for the blocxe2x80x99s criticism of his crackdown on opposition.

The arrival of more than 1,000 migrants and refugees, many from Iraqi Kurdistan, at the Polish border on Monday brought the crisis to a head. Polish border guards said on Wednesday that two groups of several dozen people had breached the borders overnight. They were arrested and expelled, they said. Lithuanian border guards said they had prevented 281 attempts to cross the border illegally on Tuesday.

At an extraordinary session of parliament on Tuesday evening, the Polish prime minister, Mateusz Morawiecki, squarely pointed the blame for the crisis at Moscow and Putin, calling the Russian leader an xe2x80x9cenablerxe2x80x9d of Lukashenko.

xe2x80x9cThis attack which Lukashenko is conducting has its mastermind in Moscow, the mastermind is President Putin,xe2x80x9d Morawiecki said in the Sejm, Polandxe2x80x99s lower house of parliament, which is dominated by the rightwing Law and Justice party.

Morawiecki said Putin was determined to xe2x80x9crebuild the Russian empirexe2x80x9d and called the crisis at the border xe2x80x9ca new kind of war, in which people are used as living shieldsxe2x80x9d.

The remarks are the most direct accusations against Russia yet in a crisis where the Kremlin has not played an overt role. Belarusian travel agencies have issued visas and brought hundreds of people from Iraq, Syria and other countries to Minsk, from where they then travel west to try to cross the border and from Poland pass on to Germany. Many of the airlines carrying the migrants and refugees are Belarusian or based in the Middle East.

Moscow has been an increasingly crucial ally for Belarus in the past year, backing Lukashenko after his brutal crackdown on protests and after his grounding of a Ryanair flight in May that set off a fresh round of sanctions and pushed Minsk further into isolation.

EU countries have threatened new sanctions and accused Lukashenko of xe2x80x9chuman traffickingxe2x80x9d and xe2x80x9cgangster-stylexe2x80x9d tactics.

On Tuesday, Russiaxe2x80x99s foreign minister, Sergei Lavrov, said western countries including EU member states, and Nato, were the xe2x80x9crootxe2x80x9d of the migrant crisis.

xe2x80x9cThey were pushing for a western-style better life and democracy the way it is interpreted by the west,xe2x80x9d he said, referring to US-led interventions and alleged western backing for the Arab spring.

Lukashenko and Putin held a phone call to discuss the border crisis on Tuesday. On Wednesday, the Collective Security Treaty Organisation, a military alliance of ex-Soviet states, said it was following the crisis xe2x80x9cvery closely and with concernxe2x80x9d.

xe2x80x9cThe migrant crisis may evolve into a great disaster for thousands of civilians, including numerous women and children,xe2x80x9d the CSTO secretariat said in a statement. Dominated by Moscow, the group is seen as the Kremlinxe2x80x99s answer to Nato.

Earlier, western media reported remarks from a Nato spokesperson that the military alliance xe2x80x9cstands readyxe2x80x9d to provide help to end the crisis.

Reuters reported on Wednesday that the EU was close to imposing more sanctions on Belarus, targeting 30 individuals and entities including the foreign minister and the Belarusian airline Belavia, with approval likely as early as next week.