Members of a German extreme right group arrested last week were believed to have been plotting "shocking" large-scale attacks on mosques similar to the ones carried out in New Zealand last year, the government said Monday.

Officials said that investigations into 12 men detained in police raids across Germany on Friday had indicated they planned major attacks, following media reports over the weekend the group aimed to launch several simultaneous mass-casualty assaults on Muslims during prayers.

"It's shocking what has been revealed here, that there are cells here that appear to have become radicalised in such a short space of time," interior ministry spokesperson Bjoern Gruenewaelder told reporters at a Berlin press conference.

"It is the task of the state, and of course of this government, to protect free practice of religion in this country, with no reference to what religion it might be," Chancellor Angela Merkel's spokesperson Steffen Seibert said.

"Anyone practising their religion in Germany within our legal order should be able to do so without being endangered or threatened".

Suspended policeman

According to media reports, the group planned to use semi-automatic weapons to copy last March's attacks in Christchurch in New Zealand in which 51 people were killed at two mosques.

Investigators learned about the plot from someone who had infiltrated the group, the reports said.

The alleged leader of the group, which was known to the authorities and whose meetings and chat activity had been under observation, had detailed his plans at a meeting organised with his accomplices last week.

According to German daily Bild, the leader was a 53-year-old from Augsburg named by investigators as Werner S.

Prosecutors said Friday they had launched early morning raids to determine whether the suspects already had weapons or other supplies that could be used in an attack.

Of the 12 men arrested on Friday, four are believed to have founded the group while eight more had promised to support them with money and weapons.

The suspects, all of whom are German citizens, also included a police officer previously suspended over his links to the far right, North-Rhine Westphalia state interior minister Herbert Reul said on Friday.

Bild claimed to have identified him as Thorsten W., a 50-year-old medieval history enthusiast whose posts online included pictures of himself with a sword and shield and rants describing Germany as a "radical left dictatorship".

'Vigilant'

German authorities have turned increased attention to the country's underground extreme right scene since the murder of conservative local politician Walter Luebcke last June.

In an October attack on a synagogue in eastern city Halle, an assailant armed with home-made weapons killed two people at random on the street and in a Turkish restaurant after failing to breach the temple's solid wooden door.

Interior ministry spokesman Gruenewaelder said police have identified around 50 extreme right adherents as "dangerous" individuals who could carry out a violent attack, compared with 660 Islamists and fewer than 10 far-left extremists.

In the summer of 2019, authorities arrested more than 30 people linked to a neo-Nazi movement called "Northern Cross".

They were suspected of planning to murder a number of leftwing and pro-migrant figures after ordering body bags and quicklime, a chemical often spread at mass grave sites, regional newspaper group RND reported.

On Monday, Gruenewaelder said that the latest arrests "prove that the security services are remaining vigilant".