People walk around in the reopened Christmas market at the Breitscheid Square in Berlin on Dec. 22, 2016. The Christmas market was attacked on Dec. 19, 2016, leaving 12 people dead and 56 others injured. (Xinhua/Shan Yuqi)

BERLIN, July 5 (Xinhua) -- Germany is facing more threat from Islamist extremists and the chance of an Islamist attack remains high, according to a report published Tuesday by the country's Federal Office for the Protection of the Constitution (BfV).

The report said there were 24,000 individuals potentially affiliated to Islamic fundamentalism in Germany. The number of ultra-conservative "Salafists" rose last year to 10,100 -- up from 8,350 the year before. Of these, some 680 have been classified as "endangerer."

The BfV considered it highly probable that there were further "active and former members, as well as those who sympathise with terrorist organizations," like the so-called "Islamic State" (IS) among those arriving in Germany.

"We have to assume that we can expect further attacks by individuals or terror commandos in Germany too," BfV chief Hans-Georg Maassen said while presenting the report in a press conference in Berlin alongside Interior Minister de Maiziere.

While receiving the most refugees and asylum-seekers from the war-torn Middle East countries, Germany in recent years has suffered several terrorist attacks.

One of the most deadly cases took place in December last year, as a truck was deliberately driven into the Christmas market next to the Kaiser Wilhelm Memorial Church in Berlin, leaving 12 people dead and 56 others injured.