GENEVA, Aug 17 (Reuters) - The top United Nations human rights official expressed fear on Tuesday for the safety of thousands of Afghans who have worked on human rights issues, while the U.N. refugee agency called for a halt to forced deportation of Afghan asylum seekers. "We are particularly concerned about the safety of the thousands of Afghans who have been working to promote human rights across the country, and have helped improve the lives of millions," Rupert Colville, spokesperson for Michelle Bachelet, the U.N. High Commissioner for Human Rights, told a briefing. Shabia Mantoo, a spokesperson of the U.N. refugee agency UNHCR, said it had issued a "non-return advisory" to states calling for a halt to forced returns of Afghan nationals including asylum seekers whose claims had been rejected. Austria, which has insisted that it plans to keep deporting illegal immigrants back to Afghanistan even as the Taliban seized Kabul, on Monday suggested setting up "deportation centres" in nearby countries as an alternative. read more Austria was one of six European Union member states that warned the European Commission last week against halting the deportation of rejected Afghan asylum seekers arriving in Europe despite the Taliban"s advances. Since then, three of the six - Denmark, Germany and the Netherlands - have reversed course. Mantoo said that the UNHCR guidance had been issued in light of discussions in several European countries and it welcomed some suspensions of deportations as "good news". More than 550,000 Afghans have been uprooted within the country since January, but the number of people crossing international borders in the last days has been "very limited", although the UNHCR has no comprehensive figures, Mantoo said.