By Tsvetelia Tsolova and Angel Krasimirov
SOFIA (Reuters) - An Afghan asylum seeker was fatally wounded by Bulgarian border police when a warning shot ricocheted, Bulgarian officials said on Friday, in what the United Nations said was the first incident of its kind in the current migration crisis.
The man was traveling with a large group of refugees from Afghanistan when confronted late on Thursday by a police patrol near the southeastern Bulgarian town of Sredets.
"We, at UNHCR, are deeply shocked by this incident," said Boris Cheshirkov, a spokesman for the U.N. refugee agency.
"We deplore the death of an Afghan asylum seeker, trying to reach safety across the border. We call on the Bulgarian authorities to conduct an immediate, transparent and independent investigation. Seeking asylum is an universal human right and not a crime."
The death prompted Bulgaria's President Rosen Plevneliev to call for rapid action co-ordinated by the European Union to tackle the crisis. The EU this week has offered Turkey aid and closer ties in return for Ankara's help in staunching the flow of migrants.
Prime Minister Boiko Borisov left an EU summit on refugees in Brussels and returned home after hearing of the incident.
The UNHCR said it was the first time an asylum seeker had been shot dead while trying to cross into Europe, which is struggling with an influx of hundreds of thousands of people fleeing war or poverty in Africa, the Middle East and Asia. More than 3,000 others have died, mainly by drowning.
The incident happened when a patrol of three officers was trying to contain a group of about 50 people some 30 km (18 miles) from the Bulgarian-Turkish border, said Georgi Kostov, chief secretary of the interior ministry.
"They put up resistance during the arrest," he told a news conference. "According to one of the officers, a warning shot has been fired in the air and one of the migrants was wounded by a ricochet and later died."
Kostov said the men, who were said to be of Afghan origin and aged between 20 and 30, were detained and in good condition.
Bulgarian prosecutors are investigating the incident.
Last year the campaign group Human Rights Watch accused Bulgaria of violating the rights of asylum seekers by forcing them back across its border into Turkey, sometimes violently. Bulgaria denied the accusation.
The Black Sea state, a member of the European Union but not of its open-border Schengen Area, has deployed more border police, installed cameras and motion sensors, and is extending a security fence to cover 160 km (100 miles) of its frontier with Turkey.
Some 11,000 asylum seekers have entered Bulgaria since the start of 2015 and their number is expected to reach 15,000 by the end of the year. Most use Bulgaria as a transit route to wealthier countries such as Germany and Sweden.
(Editing by Matthias Williams and Tom Heneghan)