BERLIN - German authorities conducted raids across the country on Wednesday, seizing explosives and arresting four people accused of founding a right-wing extremist group to attack mosques and housing for asylum seekers.

Police arrested three men and a woman accused of leading the group during raids by some 250 investigators on homes in Saxony and four other states, the federal prosecutor's office said in a statement.

Prosecutors allege the four helped found the “Old School Society” group and were planning to attack asylum-seeker housing, mosques and well-known members of the Islamic-extremist Salafist scene in Germany.

The four arrested, identified only as Andreas H., 56, Markus W., 39, Denise Vanessa G., 22, and Olaf O., 47, are being held on terrorism charges and are also accused of having procured explosives.

The statement identified Andreas H. and Markus W. as the group's president and vice-president.

“According to current investigations, it was the group's goal to conduct attacks in smaller groups inside Germany on well-known Salafists, mosques and asylum-seeker centres,” the statement said. “For this purpose the four arrested procured explosives for possible terror attacks by the group.”

Prosecutors said they are still trying to determine whether the group had concrete attack plans and refused to comment beyond their written statement.

Inquiries made to an apparent cellphone number and email address for the group were not immediately returned.

Right-wing extremists have been a renewed focus for German intelligence agencies after it came to light that a neo-Nazi group calling itself National Socialist Underground, or NSU, allegedly killed eight Turks, a Greek and a policewoman between 2000 and 2007. It is also believed to be behind two bombings and 15 bank robberies.

The group's sole survivor, Beate Zschaepe, and four alleged supporters are currently on trial in Munich.

The group's existence only came to light in late 2011, after Zschaepe's alleged accomplices, Uwe Mundlos and Uwe Boenhardt, died in an apparent murder-suicide following a botched bank robbery.

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David Rising contributed reporting.