BERLIN (Reuters) - German police seized large quantities of guns and ammunition in raids on four locations in Berlin linked to a 40-year-old German man with suspected Islamist ties, the Berlin prosecutor s office said on Wednesday.  The man, a German citizen with a Turkish background, had previously been convicted of weapons violations, and frequented a mosque which was under surveillance by state security, said prosecutor spokeswoman Silke Becker. Germany was hit by several Islamist militant attacks in 2016, including one in Berlin in December in which a Tunisian man shot dead a Polish lorry driver and then killed 11 more people by driving the stolen truck into a Christmas market. Germany s domestic intelligence agency has warned of further attacks by radicalised Muslims, given growing numbers of foreign fighters returning from war zones in Syria and Iraq. [L2N1MU194] Becker said an investigation had been under way since summer, but the raids were triggered by concerns that the suspect could harm his family rather than any specific indication of a planned terrorist attack.   It became clear that the suspect could have an Islamist background and Islamist connection in the broadest sense,  she said.  The suspect was due to go before a judge on Wednesday. 