By Gabriela Baczynska
BRUSSELS (Reuters) - The European Commission on Wednesday took another step in its unprecedented investigation into the rule of law in Poland, saying it would send its criticisms to Warsaw by Monday unless it saw "significant progress" by then.
The EU executive launched its inquiry into whether the rule of law is under threat in Poland after a new nationalist-minded government sought changes in the country's constitutional court that critics said undermined democratic checks and balances.
This has led to an effective paralysis of the tribunal, which has become the focus of heated political dispute.
The Commission has not disclosed the contents of the text, or 'opinion', it plans to send to Warsaw but it has expressed concern over conflicts around the appointment of judges to the tribunal and over new disputed laws amending the court's work that have undermined its ability to review new legislation.
"As long as Poland's Constitutional Tribunal is prevented from fully ensuring an effective constitutional review, there can be no effective scrutiny of compliance with fundamental rights of legislative acts," the Commission said in a statement.
The Commission said Warsaw would have two weeks from Monday to respond to the 'opinion' and then should work with Brussels to remedy problems it has identified. If that does not happen in a "reasonable time", the Commission can set Warsaw a formal deadline to deliver.
Failing that, Brussels can trigger Article 7 of the Treaty of the European Union and move towards the maximum sanction of stripping Poland of its voting rights in the European Council, which groups EU governments.
Such a move is regarded as unlikely, but Warsaw's handling of its constitutional crisis has already strained its ties with Brussels.
Some EU countries, already annoyed with Poland over its refusal to show greater solidarity in tackling Europe's migration crisis, want Brussels to push Warsaw hard and have threatened to use a looming review of the EU's joint budget to syphon some funds away from the bloc's largest eastern state.
Others, however, say Brussels should avoid a spat with Poland at a time when the migration crisis is testing EU unity and fuelling Euro-scepticism across the continent.
The Euro-sceptic government in Warsaw has so far offered few concessions to Brussels, saying it has a strong electoral mandate to carry out changes it deems necessary. It also says the top court had been too closely allied with the former centrist, pro-EU government.
(Reporting by Gabriela Baczynska; Editing by Gareth Jones)