BERLIN (Reuters) - A German minister rebuked Greek authorities on Thursday for letting a convicted Afghan criminal slip through the system and make it to Germany where he sought asylum and is now under arrest on suspicion of rape and murder.

The case of the 17-year old Afghan, arrested this month in the city of Freiburg, has stirred outrage in Germany and spurred politicians, including Chancellor Angela Merkel, to warn against making generalizations about migrants.

Interior Minister Thomas de Maiziere said the suspect, identified only as Hussein K., had been convicted of attempted murder in Greece 2013 and sentenced to 10 years behind bars. Released in 2015 on parole, he disappeared and came to Germany.

De Maiziere criticized Greece for launching only a national, not international, search. German police arrested him on Dec. 2 on suspicion of raping and murdering a 19-year old student who was cycling home from a party.

“This is a very exasperating incident. We will certainly have to discuss it with the Greek side,” de Maiziere told reporters, adding there needed to be more international cooperation on the exchange of information on criminals.

Crimes committed by migrants are a highly sensitive subject in Germany after nearly 900,000 migrants reached the country last year, fuelling fears they could not be properly integrated.

Merkel, standing for a fourth term in next year’s election, has seen her popularity wane due to her open-door migrant policy. At the same time, support for the anti-immigrant Alternative for Germany (AfD) has grown.

The AfD has seized on the Afghan case, as it did after hundreds of women were sexually assaulted and robbed by men of North African and Arab appearance at the last New Year celebrations in Cologne.

Germany on Wednesday deported a group of 34 Afghans, the first group to be sent back after their asylum applications were rejected under a bilateral deal agreed this year.