"Hence, the German-Polish border remains a flashpoint," the police said in a statement.
The number of illegal migrants coming to Germany from Belarus through Poland skyrocketed to 474 in August from 26 recorded between January and July.
The number of illegal arrivals with what the German police call "Belarusian connection" surged by 2,049 in September, 5,294 in October and 2,849 in November. Police recorded 521 illegal crossings as of December 29.
The European Union accuses Belarus of waving through migrants, most of them from the Middle East and Africa, to get back at it for crippling economic sanctions, a claim denied by President Alexander Lukashenko. Belarus blames EU neighbors for pushing vulnerable people back across the border.