U.N. refugee chief warns EU against carrot-and-stick approach to migration

An EU sign is seen as a migrant rests at the border crossing from Slovenia in Trnovec, Croatia October 19, 2015. The Balkans faced a growing backlog of migrants on Monday, thousands building up on cold, wet borders after the closure of Hungary's southern frontier diverted them to Slovenia. REUTERS/Antonio Bronic - RTS52GL

BRUSSELS (Reuters) - Linking aid for countries in the Middle East and Africa to how they manage migration can create dangerous precedents, the top United Nations' refugee official warned the European Union on Monday.

Overwhelmed by the arrival of more than a million refugees and migrants in 2015, the EU has tightened its external borders and sought to strike deals with countries along the migration routes to contain the flow of people.