Authorities in Germany are struggling to cope with the threat posed by Islamist terrorism, with police warning that the nation houses hundreds of extremists willing to carry out attacks.

According to the Welt am Sonntag, Germany has seen a quadrupling of the number of terror-related cases in just one year, with prosecutors having opened more than 900 so far in 2017, compared with 250 cases initiated throughout 2016.

Around 705 Islamists who are living in Germany have been identified by the Federal Criminal Police Office (BKA) as posing a terror threat to the nation. While some of these extremists have been locked up, authorities say radicalisation is a major problem in German prisons.

Local media reported this week that a “highly dangerous” Lebanese migrant who officials classify as a “threat to internal security” in Germany will soon be released from prison despite his having threatened to carry out attacks on non-Muslims.

Mohammed A. was radicalised while serving a three and a half year term for robbery, according to authorities in Berlin, who warned in an official statement that the 27-year-old plans to “use every opportunity for an attack on unbelievers” after his release from detention.

The rising terror threat is likely to play a role in coalition talks between parties, with the Free Democratic Party (FDP) calling for Germany to deport foreign Islamists.

The country’s judiciary requires greater numbers of staff as a result of the “overload” in terror-related cases, according to FDP deputy federal president Wolfgang Kubicki  — who sits on the party’s negotiating team in talks hoping to form a coalition government with the centre-right Union parties, and the Green party.

“Expulsion for Islamists who are not German nationals needs to be compulsory and enforced,” he told the Welt am Sonntag.

Angela Merkel’s Christian Democratic Union (CDU) was significantly weakened at federal elections last month, as Germans voters protested at the polls the chancellor’s decision to open Europe’s borders to an unprecedented influx of migrants from the third world in 2015.

A report published in August found that refugees and asylum seekers have been involved in more than half of terror plots in the country since the onset of the migrant crisis.

“There were no plots in Germany in 2014, and only two in 2015. In 2016, this increased eightfold,” wrote the Heritage Foundation think tank, in its report.

“There is a straightforward reason for this: In 2015, Germany took in over 1 million refugees and 2016 saw a surge in plots involving refugees.”