Four people were found dead Sunday on the Belarus-Polish border according to officials from both countries, a week after Warsaw imposed a state of emergency following an influx of migrants.
Poland's border guards added that they had also discovered eight exhausted migrants stuck in marshy terrain elsewhere along the border. Seven of them were hospitalized.
In recent months thousands of migrants, mainly from the Middle East, have crossed or tried to cross the border from Belarus into the neighboring European Union member states of Latvia, Lithuania and Poland.
The EU suspects the influx is being orchestrated by Belarusian strongman Alexander Lukashenko in retaliation against sanctions on his government.
"Today (Sunday) the bodies of three people were discovered in the border region with Belarus," Poland's border guards tweeted on Sunday.
The individuals were found in three different places and were "likely illegal immigrants," border guard spokeswoman Anna Michalska told the Polish news agency PAP.
A fourth body, of an Iraqi woman, was found Sunday on the Belarus side of the border.
"The body of a woman of non-Slavic appearance was discovered within a meter of the Belarus-Poland border," a Belarusian border official told state news agency Belta.
The acting head of the Usovo border post, Yevgeny Omes, said there were "clear signs" on the ground of the body being dragged from Poland into Belarus.
Belta said that three children, a man and an elderly woman were found near the body. They are all Iraqi citizens, Belta added.
Belta reported that the dead woman's husband said that Polish law enforcement drove them to the border and "under threat" forced them to cross over to the Belarusian side.
Poland's border guards tweeted earlier Sunday that they had also spent several hours rescuing migrants stuck in swampland off the river Suprasl by the border with Belarus.
"Eight immigrants (five men and three women) were saved, seven of them hospitalized," the border guards tweeted, adding that firefighters, rescuers and police officers also took part in the operation.
They also said Saturday was an intense day, noting 324 attempts to illegally cross the border from Belarus to Poland.
Poland last week imposed a 30-day emergency measure that bans non-residents from the area along its border with Belarus, the first time the country has used such a measure since the fall of communism in 1989.
It has also sent thousands of soldiers to the border and started building a barbed wire fence.
In early August, Belarus said it discovered a dead Iraqi man near its border with Lithuania, claiming he was murdered.
Western governments have placed several sets of sanctions on Belarus over a crackdown on dissent that began when protests erupted across the country following a disputed election last year.