German federal prosecutors have taken over the investigation of four Islamic extremists alleged to have been plotting to assassinate the leader of a far-right party.

Prosecutors said in a statement Monday there is enough evidence that the four had formed a terrorist group for federal jurisdiction.

The four suspects are part of the ultraconservative Salafi movement, which has faced increasing scrutiny in Germany since members clashed last year with Bonn police at a demonstration of the small far-right pro-NRW party.

Two suspects were arrested in Leverkusen last week after scoping out the pro-NRW leader's home, and two others in Essen and Bonn. In a Bonn apartment authorities found a list of pro-NRW's leaders, a firearm, ammunition, and 600 grams of ammonium nitrate, which could be used to make a bomb. - Sapa-AP