Berlin, October 3 (RHC)-- Three police vehicles in Germany's eastern city of Dresden have been set on fire in the run-up to a national day and less than a week after far-right extremists carried out two attacks in the city.

No one was injured in the Saturday night incident, a police source said, adding that the "politically motivated" arson attack had been carried out in retaliation for increased security measures and police presence for the 26th anniversary of the reunification of West and East Germany in 1990, known as the German Unity Day, which is being marked on Monday.

The perpetrators of the arson attack have not been arrested yet, but police have launched an investigation into the matter.  A man initially arrested on suspicion of writing hateful graffiti prior to the incident is being questioned to determine potential links between the graffiti and the arson attack.

On September 30, Dresden Police President Horst Kretschmar said some 2,600 police officers would be on duty to provide security for about 750,000 visitors expected to attend the national festivities in the eastern city.

German Chancellor Angela Merkel, who is originally from Dresden, and President Joachim Gauck, a former pastor in East Germany, are scheduled to attend the commemoration ceremony.

On September 26, two bomb attacks hit near Fatih Camii Mosque in Dresden's eastern neighborhood of Cotta and the International Congress Center.  Police at the time assumed "a xenophobic motive" behind the assaults.

Dresden, with a population of nearly 550,000, is known for far-right views and xenophobic sentiments.  The city has been a hotspot for anti-Muslim activities since 2014, when an extremist anti-Islam and anti-refugee movement known as PEGIDA was founded there.

The movement had lost its popularity until the outbreak of the refugee crisis in Europe, particularly Germany.  At its height at the start of 2015, PEGIDA managed to attract some 20,000 supporters and hold weekly rallies.  The September 26 attacks came soon after the xenophobic group staged its latest march through the city.

Over the past several months, Germany has witnessed a rise in hate crimes against refugees and Muslims.  Since the beginning of this year, refugee shelters across the country have reportedly come under 650 xenophobic attacks.