Military police in the Netherlands carrying out additional security patrols at Schiphol Airport in Amsterdam yesterday. Security has been stepped up in and around the airport following a threat, the authorities said.

No details of the possible threat were given to the media. The national threat level in the Netherlands was unchanged at "substantial", or one notch below the highest.

A nun participating in World Youth Day 2016 undergoing a security check before the Stations of the Cross mass with Pope Francis in Blonia Park in Krakow, Poland, over the weekend. World Youth Day 2016, which is being held in Krakow and nearby Brzegi, will end today.

Pilgrims had been told to expect lengthy security checks due to the huge number of people and the heightened terror threat in Europe.

A National Public Security Force officer standing guard inside the Olympic Park precinct in Rio de Janeiro yesterday.

Brazilian police are stepping in to take over security screening outside Olympic venues after a private firm failed to hire enough staff in time for the Games which open on Aug 5, the Ministry of Justice was reported to have said.

Tens of thousands of military and police personnel will be on guard during the Games.