JEDDAH: Law authorities implemented heightened security measures across Europe for the long Christmas weekend following the deadly Berlin market truck attack.

Police boosted their presence in popular tourist spots in many cities, particularly in Britain, France and Germany.

The truck attack in Berlin that left 12 people dead and the subsequent killing of the suspected driver, 24-year-old Anis Amri, by police during a routine traffic stop in Italy, have increased fears that militants might stage an attack during the most important Christian holiday of the year.

Security agencies in Rome prevented vans and trucks from entering the city center while heavily armed police patrolled the area in anticipation of Pope Francis celebrating Christmas Eve Mass in St. Peter’s basilica.

In France, where 130 people died in a terrorist attack in Paris in November 2015, 91,000 police officers and soldiers were deployed with a focus on protecting churches. And in Britain, police stepped up security at churches, Buckingham Palace and major shopping centers and landmarks that attract large numbers of tourists. Britain's terror threat is set as “severe.”

Airports and rail stations in Germany also have been reinforced with heavily armed police patrols that conduct random border checks on people entering the country. Germany’s increased patrols come as more than 100 police investigators work to determine whether Amri had accomplices in his Christmas market attack.

“The level of threat remains high,” said German Interior Minister Thomas de Maiziere on Saturday.

Police are attempting to determine whether Amri sought safe haven from confederates in Italy or if he had intended to flee to another country. In addition, Tunisian law authorities arrested Amri’s nephew, identified as 18-year-old Fedi, and two other men. The nephew is suspected of having contact with Amri, who reportedly urged the teenager to pledge allegiance to Daesh.

Juan Ignacio Zoido, interior minister of Spain, said Spanish intelligence services were investigating a possible Internet communication between Amri and a Spanish resident on the day of the Dec. 19 Berlin attack.

Meanwhile, US police and the FBI stepped up security following an FBI bulletin issued to law enforcement agencies that Daesh supporters have been urging sympathizers to attack US churches and holiday gatherings. Federal authorities, however, said there was no credible information that pinpointed specific attacks.

“The FBI is aware of the recent link published online that urges attacks against US churches,” the FBI said in a statement. “As with similar threats, the FBI is tracking this matter while we investigate its credibility.”

In a related development, a man and woman were charged with terrorism-related offenses in a London court. Munir Hassan Mohammed, 35, is charged with preparing an act of terrorism, being a member of the Daesh extremist group, and possessing instructions about how to build an explosive device inside a mobile phone. Rowaida El-Hassan, 32, faces similar charges but is not accused of Daesh membership. Both are being held pending their next court hearing.

In another incident, 16 people were wounded in an attack when a grenade exploded outside a Catholic church during Christmas Eve mass on Mindanao Island in the Philippines.

Midsayap town police chief Bernardo Tayong told wire agency reporters that most of the injured had been standing outside the Sto. Nino parish church in Midsayap town, North Cotabato.

Father Jay Virador said the blast sent the congregation fleeing. “There was no more concluding prayers as there was a commotion,” Virador said. “People hurriedly left the Church.”

The US Embassy in Manila said citizens had been warned against traveling to volatile southern islands due to kidnapping and bombing threats.

In September, 14 people died and 70 were wounded when an improvised bomb exploded in a crowded market in Davao City, hometown of President Rodrigo Duterte. Nine people, who were linked to a Daesh-affiliated group have been arrested for the attack.