Preacher among five men arrested in Germany on suspicion of being Isis recruiters

German police have arrested five men suspected of being recruitment agents for the Islamic State (Isis). The country has been on high alert since terror attacks in July.

The men were arrested in the states of Lower Saxony and North Rhine-Westphalia. The Lower Saxony raid was in the city of Hildesheim, which is home to a sizeable number of fundamentalist Muslims known as Salafists. A mosque in the city was raided in late July.

The most high profile person arrested was Iraqi national Ahmad Abdulaziz A, 32, also known as Abu Walla, or the "preacher without a face". His last name has not been published in line with German privacy laws. Abu Walla has openly spoken out in support of Isis and approved the departure of young Germans to fight with the group in Syria, according to Fox News.

The other men arrested are 27-year-old German Mahmoud O, Ahmed F.Y, 26 from Cameroon, German-Serbian Boban S, 36 and 50-year-old Turk Hasan C. The men are charged with recruiting, and providing financial and logistical help to Isis. Federal prosecutors do not believe they are linked to Jaber Albakr, who killed himself in prison in Leipzig in October after being arrested for plotting to blow up an airport.

Chancellor Angela Merkel's open door policy, which has seen more than a million refugees arrive in the past two years, has angered many Germans, who believe the country has consequently become more vulnerable to terror attacks. According to Reuters, Germany's domestic intelligence agency estimates there may be up to 500 jihadists willing to commit violence and a further 8,400 ultra-Conservatives who support their aims.

Although Germany has so far been spared terror attacks on the same scale as other European cities, two separate attacks were carried out by refugees in the summer.

In one, a teenager from Afghanistan attacked passengers on a train with an axe before being shot dead. In another, a failed asylum seeker blew himself up in a failed attack at a music festival. There were also a number of other attacks that police refused to link directly to terrorism.