Controversial plans for an EU Border and Coast Guard force are to be set out as part of an EU drive to curb the record influx of migrants.
The European Commission is proposing a force with a stronger mandate than the EU's current Frontex border teams.
But some governments see the powers as violating national sovereignty.
The commission is also proposing to resettle Syrian refugees directly from camps in Turkey to try to stop people taking the dangerous voyage by sea.
Poland says it will oppose any move to send in EU border guards without the host country's approval.
Foreign Minister Witold Waszczykowski said such powers "would mean that this would be an undemocratic structure, not controlled by the member states".