Eighteen migrants were injured while trying to reach the European Union by crossing illegally from Bosnia into Croatia, Bosnian officials said on Wednesday.
The migrants, all men from Pakistan and Iraq, were taken to a local hospital overnight by police, the officials said, declining to give further details. Doctors said all of them were released after it was determined they did not have serious injuries.
Several men with their hands and arms in casts told Bosnian regional television that the Croatian police had beaten them, taken away their mobile phones and pushed them back to Bosnia.
Croatian police said they had prevented 18 men from illegally crossing into Croatia on Tuesday night but that according to information gathered so far, the officers had not used force.
"There were no visible injuries on these people nor did any of them ask for medical assistance," the Croatian police said in a statement, adding that the Interior Ministry will investigate allegations that migrants were injured by police.
More than 40,000 migrants and refugees have entered Bosnia since last year in the hope of crossing from the northwestern towns of Bihac and Velika Kladusa into Croatia and thence travelling to western Europe.
Many have accused Croatian police of beating them before turning them back, allegations that the Croatian police have repeatedly denied.
Bosnian border police said that the case had been placed under the jurisdiction of the state prosecutor. Incidents involving migrants at Bosnia's borders are usually dealt with by local officials.
"The prosecution... is taking action together with law-enforcing agencies to determine all circumstances of the event," a prosecution spokesman said.
Bosnia, which is not an EU state, was largely bypassed during Europe's refugee crisis, which peaked in 2015. It has seen a sharp increase in migrant arrivals since the following year, when EU members Hungary, Slovenia and Croatia began closing their borders.