BERLIN (REUTERS/AFP) - German police arrested a 16-year-old Afghan youth on Sunday on suspicion of a connection to the killing of nine people by an 18-year-old gunman in Munich, authorities said.

The youth was under investigation for possibly having failed to report the plans of the gunman, who later shot himself, and may have played a role in a Facebook posting that invited people to a meeting near the Munich train station, a police statement said.

"We suspect that this boy aged 16 years could have been aware of the act," police said in a statement following Friday's shooting spree after which the 18-year-old German-Iranian attacker, David Ali Sonboly, killed himself.

The arrest is the first in the investigation.

The teenager "handed himself in to police shortly after the killing spree and had been questioned on his relationship with the perpetrator," the statement added.

But officers had "uncovered contradictions in his statements" and he was now being held in custody for withholding information about a crime.

After Friday's killings, it emerged that Sonboly set up a fake Facebook account in May, stealing the profile of a real user and sending out invitations to lure people to a McDonald's restaurant.

There was no evidence, however, that any of the people who had interacted with Sonboly via the fake account had responded to the invitation in which he offered meals and drinks.