An Iraqi man preacher accused of recruiting fighters for Daish in Syria and Iraq, including two believed to have killed more than 150 Iraqi soldiers in suicide bombings, went on trial in a German court on Wednesday.

Four alleged members of the Islamist network he had set up also stood trial.

Prosecutors say the 33-year-old preacher, identified as Ahmad Abdulaziz Abdullah A. in court documents, recruited at least seven individuals who ended up travelling to the Middle East where they fought alongside Daish militants.

Two died in two separate suicide bombing attacks against Iraqi army positions in 2015 in which more than 150 soldiers were killed, prosecutors said. The two recruits, identified as Mark and Kevin K, joined Daish in 2014.

The main suspect, known by the nickname Abu Walaa, which in Arabic means Father of Loyalty, and the four others -- a Turk, a German, a Serbian-German dual citizen and a national of Cameroon -- were arrested in November in raids in the states of Lower Saxony and North-Rhine Westphalia. They have been held in custody since then.

The defendants have chosen to remain silent during the trial.

The men had held religious lessons during which potential recruits were handed radical Islamic material, prosecutors said.

Prosecutors believe Abu Walaa preached at the Fussilet Mosque in Berlin, which was attended by a failed asylum seeker who killed 12 people at a Christmas market in the German capital last year.

"The federal prosecutor essentially accused the suspects of being members of and supporting a foreign terrorist organisation," a spokeswoman for the Higher Regional Court in the northern city of Celle said.

Michael Murat Sertoez, a lawyer for one of the suspects, said: "There will be a lot of protected witnesses who will testify and that is not acceptable for us".