In a report, Human Rights Watch criticized the European Commission, the EU's executive branch, for saying last month that Croatia is ready to join the so-called Schengen Area, a zone including 26 European states where people travel freely without ID checks.
"Croatia's unlawful and violent summary returns of asylum seekers and migrants should disqualify it from joining the Schengen Area," said Lydia Gall, senior Eastern Europe and Balkans researcher at Human Rights Watch.
The commission's recommendation, according to Human Rights Watch, "sends the message that serious human rights abuses are no obstacle to Schengen accession." As a result, it said the EU should investigate reports of abuses "instead of rewarding Croatia."
Responding to the report, Croatian police in a statement on Friday rejected accusations of migrant abuse, saying the HRW report "includes very general statements about the alleged inhuman treatment by Croatian police against migrants and does not include any concrete evidence."
The statement added that migrants often "falsely accuse police officers of violence, expecting that such accusations would help them in a new attempt to enter the Republic of Croatia and continue toward destination countries."
Earlier, Tove Ernst, a commission spokeswoman working on migration, said the EU was in contact with Croatian authorities and the authorities had promised to investigate the allegations. "When it comes to allegations of mistreatment on migrants, the Commission always takes such allegations very seriously," Ernst said. "We consider that Croatia continues to fulfill its commitment in relation to the protection of human rights."
In December 2018, the EU granted Croatia 6.8 million euros ($7.5 million) in emergency funding, principally to ensure border guards respect the fundamental rights of migrants. Human Rights Watch said it has documented "summary collective expulsions" of migrants from Croatia to neighboring Bosnia and Serbia since 2016.
It lambasted Croatian police officers for "pummeling people with fists, kicking them, and making them run gauntlets between lines of police officers" and that violence has been directed against women and children.
"Unlike with lawful deportations, migrants are not returned at ports of entry, but rather in remote border areas, including, at times, forced to cross freezing streams," according to Human Rights Watch.
Croatia joined the EU in 2013. The decision to allow Croatia to join the Schengen area must be upheld by all EU governments.