Poland's ruling conservatives have criticised as "blackmail" threats from the European Union to halt the country's voting rights in the bloc "immediately" if it pushes through a court overhaul that could see a mass dismissal of supreme court judges.

The threat is in the shape of Article 7, a never-before-used EU process designed to uphold the rule of law. It is regarded as a so-called nuclear option that can freeze a country's right to vote in meetings of EU ministers.

The EU's threat came after Polish President Andrzej Duda signed into law two of four pieces of legislation that give the Polish government vast powers over the appointment of judges, prompting concerns about judicial independence and rule of law.

"We won't accept blackmail on the part of EU officials, especially blackmail that is not based on facts," Rafal Bochenek, Poland's government spokesperson, told the Polish news agency PAP on Wednesday.

"All the laws prepared by the Polish parliament are in compliance with the constitution and democratic rules."

Frans Timmermans, the European Commission (EC) vice president, has given Poland one month to reduce concern about the overhaul.

He said the EU "asks the Polish authorities not to take any measure to dismiss or force the retirement of supreme court judges. If such a measure is taken the commission is ready to immediately trigger the Article 7 procedure".

The EC said that, in particular, a proposed law that would lead to the dismissal or forced retirement of Supreme Court judges would "seriously aggravate the systemic threat to the rule of law".

Legal action

Separately, the EC has decided to launch legal action against Poland over the law that will affect the country's lower courts, according to Timmermans.

The legislation, which gives the justice minister the power to hire and fire the heads of Poland's lower courts, was signed into law by Duda on Tuesday.

The EU took issue with the Polish law because it introduced different retirement ages for female and male judges, which is a breach of EU anti-discrimination laws.

Timmermans said the Commission would send a letter of formal notice to Poland as soon the law was published.

Poland would have one month after the receipt of the letter to address the Commission's concerns.