The Latest on the migrant situation in Europe (all times local):

5 p.m.

The head of the U.N. refugee agency is concerned that refugees could suffer if the European Union's migrant deal with Turkey is "hijacked" by political concerns.

U.N. High Commissioner for Refugees Filippo Grandi told The Associated Press Monday that he hopes refugees do "not get hijacked by all the rest."

The EU has offered Turkey visa-free travel for Turkish citizens, fast-track EU membership talks and billions of euros for Syrian refugees if it stops migrants coming to Europe.

While refugee arrivals in Greece have slowed significantly, tensions between Ankara and Brussels are high over delays on easing visa restrictions and the slow pace of membership talks.

Grandi said linking refugees' futures to Turkey's EU concerns "makes it somehow conditional to other issues that are more complicated and difficult."


4:45 p.m.

German authorities say that 100 Bavarian police officers will reinforce federal police patrolling the country's frontier with Austria, paving the way for more thorough border checks.

The move comes as police announced Monday that 37 migrants, most of them from Eritrea, were detained in the Bavarian capital, Munich, after entering the country on freight trains.

The state of Bavaria has a conservative government that has long talked tough on the migrant crisis and wants tougher checks, criticizing Chancellor Angela Merkel's decision in September 2015 to let in asylum-seekers who were stuck in Hungary.

Germany reintroduced limited border controls at the height of last year's influx during which hundreds of thousands of migrants entered the country. Many of them were Syrians, Iraqis and Afghans seeking to apply for asylum in Germany.