The nephew of the Berlin Christmas market attacker Anis Amri and two other suspects have been arrested in Tunisia, officials say.
The three, aged between 18 and 27, were members of a “terrorist cell”, and they were detained overnight, the Tunisian interior ministry said.
Tunisian-born Anis Amri, 24, was shot dead by police near the Italian city of Milan on December 23.
This week’s truck attack at the Breitscheidplatz Christmas market left 12 people dead and 49 injured.
The interior ministry statement said Anis Amri’s nephew – the son of his sister – had confessed that he had communicated with his uncle via the encrypted chat application Telegram to evade security surveillance.
It said the three-member cell had been active in the towns of Fouchana, outside Tunis, and Oueslatia near Anis Amri’s hometown of Kairouan, about 95 miles south of the capital.
The statement added that Anis Amri had sent money to his nephew to travel to Germany and join a jihadist group, and encouraged him to pledge allegiance to ISIS.
Meanwhile, intelligence services in Spain are investigating a possible internet communication between Amri and a Spanish resident on 19 December, Interior Minister Juan Ignacio Zoido told radio station COPE.
On December 23, ISIS released a video showing Anis Amri pledging allegiance to its leader Abu-Bakr al-Baghdadi.
Anis Amri was shot dead after opening fire on police officers during a routine police check in the Milan suburb of Sesto San Giovanni, after a three-day Europe-wide manhunt.
According to a United Nations report, an estimated 5,500 Tunisians – mostly young people between the ages of 18 and 35 – were fighting in the ranks of terrorist organizations in Libya, Iraq, Syria and, to a lesser extent, Mali.
In November 2016, the ministry of the interior in Tunis said about 800 fighters had returned to the country.
Berlin’s Breitscheidplatz Christmas market has reopened following the truck attack that killed 12 people and injured 49 more on December 19.
The attacker is a suspected Islamist extremist who drove the truck into a crowd.
German police have installed concrete barriers to prevent a repeat attack.
Meanwhile police have raided homes in Dortmund, but prosecutors denied reports that arrests linked to Tunisian suspect Anis Amri were made.
Anis Amri’s ID was left in the truck and now his fingerprints have been found on the door, reports say.
The truck attack victims included at least six Germans and an Israeli tourist.
Image source Twitter
German newspaper Bild quoted the federal prosecutor’s office as saying four people who were in contact with Anis Amri had been arrested.
However, a spokesman for the prosecutor’s office denied the report, saying he was not aware of any arrests.
There were also raids at a migrant centre in Emmerich in western Germany, where Anis Amri stayed briefly last year, and at addresses in Berlin.
Anis Amri’s name came to the attention of German counter-terror services last month and he reportedly moved in the circle of extremist preacher Ahmad Abdelazziz A, known as Abu Walaa, who was arrested last month and charged with supporting ISIS.
The Ruhrnachrichten news website said Anis Amri had lived in Dortmund from time to time and residents at one block of flats said he had spent time with a German of Serbian origin, Boban S., who was arrested last month along with Abu Walaa.
Anis Amri was on a US no-fly list, had researched explosives online and had communicated with ISIS at least once via the Telegram Messenger service, the New York Times reported.
ISIS has said one of its militants carried out the attack but has offered no evidence.
Anis Amri had also offered himself for a suicide attack, Spiegel magazine reported, quoting communications intercepted for the prosecution of hate preachers in Germany.
However, what he said was not believed to be explicit enough for him to be arrested, the magazine said.
Anis Amri had also been put under surveillance in Germany earlier in the year on suspicion of planning a robbery to pay for automatic weapons for use in an attack.
However, the surveillance was reportedly called off after it turned up nothing more than drug-dealing in a Berlin park and a bar brawl.
Anis Amri, 24, is said to have entered Germany in 2015 and was due to be deported in June but stayed because there was a delay in receiving paperwork from Tunisia.
He had a history of crime, serving 4 years in an Italian prison for arson and convicted in absentia in Tunisia for a violent robbery.
A police notice lists six different aliases used by Amri, born on 22 December 1992, who at times tried to pass himself off as an Egyptian or Lebanese.
The German authorities warn the suspect could be armed and dangerous and are offering a reward of up to €100,000 ($104,000) for information leading to his arrest.
It is thought Anis Amri may have been injured in a struggle with the Polish driver of the truck, found murdered in the cab.
Investigators believe the truck was hijacked on December 19 when it was parked in an industrial zone in north-western Berlin pending delivery of its cargo.