German authorities said Friday an important suspect in connection with a series of explosions in the western city of Cologne had been arrested in Paris.

The suspect, a 22-year-old, was picked up at the Roissy Airport in the French capital on Tuesday.

The public prosecutor's office in Cologne has initiated extradition proceedings and is in close contact with the French judicial authorities.   

What's behind the explosions?

Investigators believe the 22-year-old is a "key figure" in a suspected drug deal, which is said to have been behind the series of explosions that have rocked Cologne and other places in recent months.

The theft of a large quantity of cannabis from a warehouse in Hürth is believed to have triggered the spiral of violence.

A group that had been cheated out of the drugs was trying to get the cannabis back or receive compensation, investigators said recently.

According to the public prosecutor's office, more than ten people are already in custody in connection with the crimes.

sri/kb (dpa, AFP)