German police have detained four German nationals suspected of having plotted to kidnap German health minister Karl Lauterbach and destroy power facilities to cause a nationwide power outage.

"The two main suspects are to have agreed with others to attack the federal health minister," a spokesperson for the Koblenz prosecutor's office said, confirming a report by German broadcaster ARD.

The group behind a chat group Vereinte Patrioten - German for United Patriots - "intended to cause civil war-like conditions and ultimately overthrow the democratic system in Germany", the prosecutor's office earlier said in a statement.

It said authorities had searched 20 properties in several German states yesterday, confiscating weapons including guns, ammunition and a Kalashnikov assault rifle, cash in euros and foreign currency as well as gold bars and silver coins.

The prosecutor's office said the group had also planned to kidnap other well-known public figures but did not say who the targets were.

It has asked a judge to issue arrest warrants for the four detained suspects. A fifth suspect is still at large.

Mr Lauterbach said that the kidnap plot showed that radicalisation among people protesting against coronavirus restrictions now went well beyond the issue of Covid-19.

"This shows that Covid protests have not just radicalised but that this is about more than just Covid," he told a news conference.

"There are forces that intended to destabilise the state and democracy. They are using the Covid protests. This is a small minority in our society but they are highly dangerous," Mr Lauterbach said.