Croatian police are allegedly spray-painting the heads of asylum seekers with crosses when they attempt to cross the border from Bosnia. The Guardian has obtained a number of photographs of what has been described by charities as the “latest humiliation’’ perpetrated by the Croatian authorities against migrants travelling along the Balkan route. The UN has asked the Croatian government to investigate all the allegations of abuse. “It is obvious that one of the intended effects of this behaviour is to humiliate refugees and migrants attempting to cross the border,” said Jack Sapoch from No Name Kitchen (NNK), an NGO that operates in Velika Kladuša, 2km from the border, and is a member of watchdog organisation the Border Violence Monitoring Network. “As far as I see it, this is the result of either one of two motivations. Either the Croatian authorities committing these acts are using spray paint to identify and humiliate repeat border crossers or, more worryingly, they are using this as a tactic to psychologically traumatise these men – the majority of whom are Muslim – with a religious symbol,” Sapoch said. On 6 May in Poljana, Bosnia, sources reported to the NNK that a group of people had been pushed back and sprayed with orange paint. The group had also had their money and mobile phones stolen; several had their shoes taken. On 7 May, a different group returned to Miral camp outside Velika Kladuša describing similar treatment. The Croatian police have been contacted for a comment. Previously, the authorities have stressed the need to protect their borders. Every night groups of asylum seekers attempt to cross from Bosnia into Croatia, where squadrons of police await them at the border. Armed with truncheons, pistols and night vision goggles, they patrol the EU’s longest external border. Asylum seekers call crossing the border “the game,” but it is a dangerous undertaking. Aid workers, doctors, border guards and UN officials have documented systematic abuse and violence perpetrated by police, with migrants often beaten, shot, robbed and even stripped of their clothes. The UN refugee agency, UNHCR, said it was ‘‘deeply concerned about reported violence and treatment of migrants and refugees by Croatian police’’. ‘‘Our organisation has previously received and subsequently shared with the authorities credible reports of people who claim they have been unlawfully returned from Croatia to Bosnia and Herzegovina and Serbia,” Zoran Stevanović, UNHCR regional communications officer for central Europe, told the Guardian. “These reports highlight problems regarding the identification of asylum claims, violence and excessive use of force, identification of vulnerable individuals, treatment of unaccompanied children,” he said. “UNHCR has requested the Croatian government to investigate all claims of violations and abuse and to establish an independent assessment mechanism to establish the facts of the border situation.’’ Between September 2019 and January this year, the UNHCR reported to the Croatian authorities 100 cases of alleged unlawful returns from Croatia to Bosnia and Serbia. Despite this, Sapoch said that in the last two months his organisation has continued to receive reports of violence on the Bosnian border. He added: “Hearing reports of increased brutality during pushbacks is worrying due to the increased autonomy that state authorities have gained during these times of the [coronavirus] pandemic. Now, more than ever, it is important for us to keep these forces accountable for their own actions. “Pushbacks are illegal and the spread of Covid-19 is not an excuse to confront vulnerable people with even more violence. It is unacceptable.” Last month, authorities in Bosnia ordered the transfer of thousands of migrants to a remote camp in Lipa, a village about 25km from the border with Croatia, due to the coronavirus outbreak in the country. The construction of the new camp prompted panic among asylum seekers and volunteers, who fear the measure will not guarantee any assistance to migrants.