Poland this week said it had blocked a bid by hundreds of migrants to enter from Belarus and warned of an "armed" escalation with thousands more massed near the border.

Washington and Brussels called on Minsk to stop what they described as an orchestrated influx and Polish Prime Minister Mateusz Morawiecki said Tuesday the border crisis threatens the security of the entire European Union.

Belarus in turn warned Poland against escalating tensions on the border and said Warsaw's treatment of migrants would be a "litmus test" of its committment to international norms.

"We would like to warn the Polish side in advance against any provocations directed against the Republic of Belarus to justify illegal use of force against disadvantaged, unarmed people, among whom there are many children and women," the foreign ministry said in a statement.

The defence ministry meanwhile denied Polish allegations that Minsk was coordinating the wave of migrants, calling the accusations "unfounded and unsubstantiated".

The defence ministry Tuesday claimed Poland was "not committed to securing a constructive solution to this issue and is intentionally bringing the current conflict situation to a political level".

It said Poland had deployed 10,000 military personnel to the border without giving prior warning to Belarusian authorities, in what it said was a violation of joint security agreements.

Minsk said that according to the agreements, observers should be present at any deployment of more than 6,000 military personnel.

"Minsk has so far not received any notification or invitation of observers from the Polish side."

Belarusian interior minister Ivan Kubrakov told state-run news agency Belta that the migrants were in the ex-Soviet country "legally," adding: "There have been no violations of the law on the part of migrants so far."