Militant groups smuggled some of their members into Europe in the wave of migrants who have fled from Syria, German chancellor Angela said on Monday (July 11).
"In part, the refugee flow was even used to smuggle terrorists," Merkel told a rally of her Christian Democrats in the eastern German Baltic Sea resort town of Zingst.
Merkel also warned that if young people in poor parts of the world did not get "a perspective," "they will all try to get somewhere else and that's not good for the countries and it's of course also not good for us."
"Imagine a country like Togo, a small African country where 75 per cent of the population -- so three out of four people -- are younger than 25."
"All these young people might not have electricity but if they just have a little bit of money they all have a smartphone. They can all watch what the world is like elsewhere," said Merkel.
More than 1 million migrants arrived in Germany last year, many of them Syrians.
The German chancellor also commented again on British voters' recent decision to leave the European Union.
"We will have difficult negotiations with Britain, it will not be easy," Merkel said.
"But that is why we as 27 member states must ask 'how should our Europe look?," she added.