Almost 6,000 Polish soldiers are now guarding the country's border with Belarus to meet a surge in migration, Defence Minister Mariusz Blaszczak said on Tuesday.
On Saturday, before the extra posting, Mr Blaszczak said there slightly more than 3,000 soldiers on the frontier.
"Almost 6,000 soldiers from the 16th, 18th and 12th divisions are serving on the Polish-Belarusian border," he said in a tweet on Tuesday.
"The soldiers provide support to the Border Guard by protecting the country's border and not allowing it to be illegally crossed."
The European Commission and Warsaw say the flow of migrants has been orchestrated by Belarus to put pressure on the EU over sanctions it imposed on Minsk. Belarus has denied this.
Poland has declared a state of emergency in the region and plans to build a wall on the border.
Parliament has also passed legislation that human rights advocates say aims to legalise pushing migrants back over its borders, in breach of the country's commitments under international law.
As of Sunday, there had been about 9,600 attempts to illegally cross the border in October, the Border Guard said.
More migrants have also been arriving in Germany. Polish media reported that the head of the German Police trade union has asked Interior Minister Horst Seehofer to temporarily restore border controls with Poland to stop the flow.
Mr Seehofer offered to send border control officers to Poland to help it manage the influx of migrants along the border between the two EU countries.
He said in a letter to Mr Blaszczak that Germany could also offer logistical support.
Authorities in Brandenburg, the eastern German state that is housing most of the new arrivals, are calling for tougher action against Belarusian President Alexander Lukashenko's government.