In a statement, the police force said that it was carrying out searches of 14 residential and four non-residential premises, as part of the investigation into a theft of pistols from the PSP National Directorate in January 2017.

Operation Ferrocyanide, as it has been dubbed, takes in the municipalities of Vila Nova de Gaia, Gondomar, Mafra, Abrantes, Alvaiázere, Sintra, Cascais, Oeiras, Lisboa, Almada and Albufeira.

In the statement, the PSP states that it is undertaking the investigation, overseen by public prosecutors at the Central Department of Criminal Investigation and Action (DCIAP). Within the PSP, responsibility is under the Criminal Investigation Division of the Lisbon Metropolitan Command, with support from the Special Police Unit, Porto Metropolitan Command and Faro District Command.

Some 150 police officers are involved in the searches, it added.