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.
ITV News Security Editor Rohit Kachroo reports from Berlin on the ongoing hunt for an alias-using Tunisian suspect wanted in relation to Monday's Christmas market lorry attack.
A 100,000 euro (£84,000) reward has been offered for information leading to the arrest of Anis Amri, who investigators said has used a series of faked documents.
The 23-year-old, who was under covert surveillance from March until September this year, is known to have links to a 33-year-old Iraqi man arrested last month who has been described as Germany's IS leader.
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?