President Andrzej Duda decided to sign the embattled education system reform bill liquidating middle schools and reintroducing a former eight + four system, he said at a press conference on Monday.

The president told reporters that the constitutional 21-day period during which he had to take a decision regarding the bill was "very difficult”.

"I do not hide that I had many doubts and questions since the matters the bills concern are very difficult on the one hand, and very sensitive on the other […] because of a very simple reason, because they concern the future of our country, future generations and above all, children and their parents," Duda said.

He added that he had no doubts that "the Polish education system demanded repair and change".

The changes are contested by the teachers' union ZNP which plans to hold a referendum on the issue.

Opposition parties Civic Platform (PO), Nowoczesna, Razem, Inicjatywa Polska, trade union OPZZ and various civic groups declared their support for the idea of referendum.

If the president does not announce a referendum, the ZNP together with opposition parties, NGOs and parents groups will strive to collect the necessary 500,000 signatures under a petition to the Sejm lower house to hold one.

The planned reform has already sparked conflicts between some schools, local governments and regional authorities.

Critics say that the government-authored reform will be introduced without any social consultations, will introduce chaos to schools and will destroy the achievements of the educational system of the recent years.

Under the education reform, starting from the 2017/2018 school year, Poland is to return to its previous system of eight-year elementary schools followed by four-year high schools or five-year technical schools.

Currently, children in Poland attend a six-year primary school, followed by a three-year lower secondary school (middle school) and a three year upper secondary school. The system was introduced in 1999.

PO politicians on Saturday appealed to Duda to veto the education reform law since in their opinion the reform "was harmful" while its authors wanted to return to "a school of the past".