The United Nations refugee agency says the number of South Sudanese refugees in East Africa could pass 1 million this year, and it calls on armed parties to allow safe passage for people fleeing the latest fighting.

Ann Encontre, a U.N. refugee coordinator in South Sudan, said Friday there is concern about fresh outflows of refugees following military clashes in the capital, Juba. She appealed for $701 million in relief aid.

Even before the resurgence of violence in the past week, hundreds of thousands of refugees had been sheltering in Uganda, Sudan, Ethiopia and elsewhere since civil war began in December 2013.

But there are new reports that South Sudan authorities are blocking some citizens, including those with U.S. or Canadian dual nationality, from leaving the country.