berlin truck attack
A general view shows the site where a truck ploughed through a crowd at a Christmas market on Breitscheidplatz square near the fashionable Kurfuerstendamm avenue in the west of Berlin, Germany, December 20, 2016Reuters

The nephew of the Berlin market attacker Anis Amri, along with two other suspects, was arrested by the Tunisian security forces on Saturday in connection with the lorry attack that claimed the lives of 12 people and wounded another 49.

The Interior Ministry of Tunisia said that the three suspects, who are aged between 18 and 27 years and were detained overnight, were members of a "terrorist cell". He is one of three men being held in prison on "suspicion of belonging to a terrorist organisation and connections with terrorist offences," the ministry said.

Twenty-four-year-old Amri, born in Tunisia, was shot dead by the police near the city of Milan on Friday morning.

Amri's nephew confessed that he was in touch with the attacker through the encrypted chat application Telegram to evade security surveillance, BBC reported, citing the ministry's statement. Amri had asked his nephew to pledge his allegiance to the Islamic State group. 

The statement also said that the deceased attacker had sent money to his nephew so that he could travel to Germany and join the Isis.

The terrorist cell 'Abu Al Wala', consisting of three members operating for Isis from Germany, was active in the towns of Fouchana situated outside of Tunis, and also Oueslatia near Amri's hometown of Kairouan.

Spain's intelligence services are probing into a possible internet communication between Amri and a Spanish resident on December 19, BBC quoted Interior Minister Juan Ignacio Zoido as saying citing radio station COPE.

A senior Italian counter-terrorism official told CNN that Amri "had all the hallmarks of being on the run alone" when he was killed by two Italian police officers in Milan on Friday.

A video released on the terror outfit's website Amaq shows the attacker pledging allegiance to Abu Bakr al-Baghdadi and vowing that "we will slaughter" the "crusaders who are shelling the Muslims every day," CNN reported.