BRUSSELS (Reuters) - The European Commission will ask EU member states on Wednesday to take a stand on whether the Polish government is abusing democratic standards, three sources told Reuters, as the bloc steps up pressure on Warsaw.

Poland has been in a deepening dispute with Brussels and other European Union states over upholding the rule of law since the nationalist-minded, eurosceptic Law and Justice (PiS) party won power in late 2015.

PiS denies that it is undermining democratic standards in the largest ex-communist EU country but Brussels - along with many other member states, the Polish opposition and rights activists - has been sounding the alarm for months.

After German Chancellor Angela Merkel offered rare public criticism of Warsaw last week, the bloc is seen more likely to head toward an unprecedented punishment of Warsaw.

Three sources said the executive Commission will ask all EU states on Wednesday to discuss the situation in Poland again at a ministerial meeting in Brussels on Sept. 25.

The meeting is not expected to trigger the so-called Article 7 punitive procedure yet but the discussion will measure the willingness of the other 27 EU countries to move ahead.

At the heart of the dispute is a PiS reform of the judiciary in Poland which puts the courts and judges under tighter government control.