Germany saw a sharp rise in far-right violence in 2015, a year in which it took in more than a million migrants, according to a report Tuesday that called for concrete steps to avert the emergence of "right-wing terrorist structures."

The annual report prepared by Germany's domestic intelligence agency said the number of violent acts by right extremist groups or individuals jumped to 1,408 in 2015, an increase of more than 42 percent from 990 in the previous year. The incidents included attacks against journalists and politicians and attempted murder.

The report also chronicled 75 arson attacks against refugee centers in 2015, up from just five a year earlier.

Germany was home to an estimated 11,800 violent far-right extremists, the report said, roughly half of the total number of far-right individuals in the country.

"Current investigations against the suspected development of terrorist groups points to the possible emergence of right-wing terrorist structures in Germany and the need for the government to take rigorous action," the Interior Ministry said in a statement accompanying the report.

Interior Minister Thomas De Maiziere said Germany was seeing a rise in both far-right and far-left extremism and a growing willingness among activists from both sides to resort to violence.

"It is worrying that anti-immigration incitement is creeping into the heart of our society," he said in the statement.

The report said most violent acts against immigrants did not seem to be systematically orchestrated, though many of the arson attacks did bear signs of careful planning and preparation. German authorities recently broke up a suspected far-right militant group known as "Oldschool Society" and there are concerns that similar groups could emerge elsewhere.

Last year Germany took in more than 1 million migrants, the majority of them Muslims fleeing conflicts in Syria, Iraq and elsewhere in the Middle East and Africa. The influx has put pressure on public services and raised fears of increased ethnic and religious tensions.