LISBON (Reuters) - International arms dealers and militants are suspected to be behind the theft of more than 100 grenades and ammunition from a military arms depot in Portugal last week, prosecutors said on Tuesday.

The theft has grabbed attention in Portugal and prompted questions about the security at the base. Opposition politicians have called on the defense minister to resign.

The public prosecutor’s office said in a statement that the theft was “part of a much bigger reality”.

“What is suspected is ... international arms trafficking and international terrorism,” it said.

The office said the judicial police’s terrorism unit and the military police had joined an expanded investigation.