Authorities have arrested three suspected foreign operatives of Hamas they believe were preparing a serious act of violence.

Prosecutors said they suspect the three men of being involved in procuring firearms and ammunition for Hamas to be used for assassinations targeting Israeli or Jewish institutions in Germany.

The three men were arrested in Berlin.

"In the course of today's arrests, various weapons, including an AK 47 assault rifle and several pistols, as well as a considerable amount of ammunition, were found," said the federal prosecutors in a statement.

The Hamas operatives were arrested in Berlin (file pic)

The three, identified in line with German privacy laws only as German citizen Abed Al G., Wael F. M., born in Lebanon, and German citizen Ahmad I., were arrested in Berlin.

In February, four Hamas members suspected of plotting attacks on Jewish institutions in Europe went on trial in Berlin in what prosecutors described as the first court case against militants of the Islamist group in Germany.

Local media reported that anti-terror investigators observed how the accused met on Wednesday in Berlin for a weapon handover before operational forces intervened and discovered functional weapons.