Three people including the nephew of the Berlin Christmas market attacker Anis Amri have been arrested in Tunisia.
Tunisia's Interior Ministry said Amri - who was shot dead on Friday - had sent his 18-year-old nephew Fedi money to join him in Europe.
Twelve people were killed and dozens more injured in the attack on Monday.
The body of an Italian woman killed in the truck attack on a Christmas market in Berlin has arrived in Rome.
A casket containing the remains of Fabrizia di Lorenzo, 31, arrived at Rome's Ciampino airport on Saturday five days after she was killed along with 11 others in the attack.
Italian President Sergio Mattarella was present as Ms Di Lorenzo's body arrived in the Italian capital.
The victim had been living in Berlin and went to the Christmas market to buy presents to celebrate the holiday with family in her hometown of Sulmona, central Italy.
The suspected attacker, Tunisian national Anis Amri, was killed in a shootout on Friday in a Milan suburb.
The funeral for the lorry driver killed in the Berlin Christmas market attack has taken place in his home country of Poland.
Footage has emerged of the final moment before a truck ploughed into a crowd of people at a Christmas market in Berlin.
A man is being hunted by German police after a lorry ploughed into a Berlin Christmas market on Monday, killing 12, but who is the suspect?