The Polish army on Thursday said it had detained a group of about 100 migrants who crossed the Belarus border during the night, accusing Belarusian forces of leading the operation.
The incident came as Belarus, which has said it wants to defuse the crisis, prepared a first repatriation flight for migrants to Iraq that will have between 200 and 300 people on board.
Thousands of migrants, mainly from the Middle East, are camped out or staying close to the Poland-Belarus border in dire conditions aiming to cross into the European Union, in a crisis that began over the summer.
The EU says Belarus engineered the crisis in retaliation for sanctions on the ex-Soviet country. Minsk and its main ally Russia have rejected the charges and have criticised the EU for not taking in the migrants seeking to cross over.
In the latest border incident, the Polish defence ministry said that Belarusian forces had first carried out reconnaissance and “most likely” damaged the barbed wire fence along the border.
“Then the Belarusians forced the migrants to throw stones at Polish soldiers to distract them. The attempt to cross the border took place several hundred metres away,” it said.
“A group of about 100 migrants was detained,” it said, adding that the incident happened near the village of Dubicze Cerkiewne.
“Belarusian special forces led yesterday’s attack,” it said.
Video footage released by the defence ministry appeared to show Polish soldiers surrounding a large group of migrants crouched down in a wooded area at night next to some barbed wire.
Belarusian President Alexander Lukashenko, who has ruled with an iron fist for nearly three decades, has spoken to German Chancellor Angela Merkel on the crisis twice in recent days.
Lukashenko’s press service on Wednesday said the Belarus leader and Merkel “agreed that the problem as a whole will be brought up to the level of Belarus and the EU.
“Relevant officials, to be determined from both sides, will immediately start negotiations to resolve the existing problems,” it said.
Merkel’s spokesman Steffen Seibert said the German leader had “underlined the need to provide humanitarian care and return options for the affected people”.
An EU spokesman said there were “technical talks” and urged Minsk to grant humanitarian access to the border area.
Aid groups say at least 11 migrants have died since the crisis began in the summer.
They have called for a de-escalation and a humanitarian response to the problem.
Poland estimates there are between 3,000 and 4,000 migrants along the entire border, with the largest group staying close to the shut down Bruzgi-Kuznica border crossing.
The Belarusian Red Cross says around 1,000 migrants are staying in a warehouse near that crossing and 800 more are camped nearby.
Belarus said it was preparing a voluntary repatriation flight that is planned to take off from Minsk at around 1045 GMT on Thursday and will fly first to Erbil and then to Baghdad.
Several airlines have also said they are trying to stop would-be migrants from travelling to Belarus in the first place.
But officials have warned that the crisis may take time to defuse.
Polish Defence Minister Mariusz Blaszczak said Wednesday: “We have to prepare for the fact that the situation on the Polish-Belarusian border will not be resolved quickly.
“We have to prepare for months or even years,” he told Poland’s Radio Jedynka.
In an interview with AFP, Fabrice Leggeri, the head of the EU border agency Frontex, also said that the EU should prepare for more “hybrid” migrant crises engineered for political ends.
“We have to prepare ourselves for situations like this which can arise quite quickly,” he said, comparing the current standoff to one on the Greece-Turkey border last year.