Women’s rights groups have denounced police raids on their offices in several Polish cities that resulted in the seizing of documents and computers, a day after women staged anti-government marches to protest at the country’s restrictive abortion law.

The raids took place on Wednesday in the cities of Warsaw, Gdańsk, Łódź and Zielona Góra. They targeted two organisations, the Women’s Rights Centre and Baba, which help victims of domestic violence and participated in this week’s anti-government protests.

Women’s rights activists said on Thursday that the loss of files would hamper their work, and accused authorities of trying to intimidate them. Prosecutors denied the accusation, saying the timing of the raids a day after the marches was coincidental.

Some fear the ruling Law and Justice party, led by Jarosław Kaczyński, is following in the footsteps of neighbouring Hungary, where non-governmental groups have faced harassment under the prime minister, Viktor Orbán.

“This is an abuse of power because, even if there is any suspicion of wrongdoing, an inquiry could be done in a way that doesn’t affect the organisations’ work,” Marta Lempart, the head of the Polish Women’s Strike, which organised the protests, told Associated Press.

The women’s groups said they were told by police that prosecutors were looking for evidence in an investigation into suspected wrongdoing in the justice ministry under the former government. At the time the ministry provided funding to the women’s groups.

“We are afraid that this is just a pretext or warning signal to not engage in activities not in line with the ruling party,” the Women’s Rights Centre said in a statement.

Anita Kucharska-Dziedzic, who heads Baba, said police entered her office in Zielona Góra, western Poland, at 9am on Wednesday and worked until 6pm removing files.

She told AP her group was not aware of any wrongdoing by justice ministry officials it was in contact with.

She also said she now expected problems continuing her projects due to the loss of files, and is also concerned because the documents contained private information on victims of domestic abuse who had sought the group’s help.

Barbora Cernusakova, Amnesty International’s researcher on Poland, called the police operations “very worrying”.

“We understand that the police actions came in the context of an investigation against former staff of the Ministry of Justice, but the NGOs, and the women and girls they support, will suffer the consequences,” Cernusakova said.

Jacek Pawlak, a spokesman for prosecutors in Poznań, where the investigation is being led, said the raids were part of an ongoing investigation but would not divulge what the probe was about. He said there was no attempt to harass the women’s organisations.

This week’s street demonstrations came on the first anniversary of a mass Black Protest by women dressed in black that stopped a plan in parliament for a total ban on abortion.

Despite that success, women’s rights activists marched to protest that abortion was still illegal in most cases, and called for a liberalisation of the law.