Polish lawmakers are to debate a proposal to tighten already restrictive abortion rules on Wednesday, while rights activists protested on social media as coronavirus limits public gatherings.

Abortion rights are a contentious issue in Poland, one of Europe's most devout nations, with the nationalist ruling Law and Justice (PiS) party keen to burnish its conservative credentials despite considerable public opposition to further restrictions.

Proposed as a citizens' initiative, the draft legislation would ban abortion if prenatal tests show serious, irreversible damage to the foetus, one of the few instances in which the procedure is allowed in Poland.

Others are incest, rape and risks to maternal health.

PiS, a party that campaigns on introducing more religious values into public life, has signalled some reluctance to back the bill in parliament, which it controls, ahead of a presidential election on May 10.

The issue poses a dilemma for PiS, which had previously retreated from proposals to nearly ban abortion after a massive public outcry, because it could galvanise voters on either side of the divide.

Campaigners also say it would face renewed criticism if it pushed through legislation when restrictions on public life because of the coronavirus pandemic prohibit large-scale demonstrations.

"It is a difficult subject, and the timing is unfavourable," said Tadeusz Cymanski, a senior PiS lawmaker.

Deputies are due to debate the issue late on Wednesday.

TERMINATIONS ABROAD

Underscoring deep-seated support for further restrictions on the right in Poland, President Andrzej Duda told a Catholic news outlet Niedziela that he would sign further curbs into law.

"I believe that killing disabled children is simply murder," Duda, a PiS ally, was quoted as saying.

Opinion polls show Duda wining the May 10 election, although the ballot is clouded in uncertainty because of the COVID-19 pandemic.

PiS is seeking to hold the ballot via post rather than polling booths but a legislative proposal on the issue might clear parliament only days before the election date, leaving little time to organise.

The opposition has said the vote should be postponed because the election campaign has been curtailed by the pandemic, accusing Duda of taking advantage of his position to continue campaigning.

Rights activists in Poland say the pandemic has also curbed women's access to abortion abroad because of travel restrictions throughout Europe.

Many women terminate pregnancies in Germany, Slovakia and further away, in cases when it would be illegal in Poland or when hospitals refuse to perform an abortion that would technically be allowed under Polish rules.

Andrzej Rychard, a sociologist, said a vote for new abortion rules would likely undermine unity within PiS and its conservative ruling alliance, already strained by internal debates over whether the presidential vote should be delayed.

"It would remind people that they can mobilise and protest," Rychard said. "And that could shake up the ruling alliance."