Britain unlawfully gave police wider powers to impose conditions on peaceful protests which cause "more than minor" disruption to the public, London's High Court ruled on Tuesday.

Civil rights group Liberty took the government to court over changes to public order laws made last year, which it says gave the police almost unlimited powers to shut down protests.

The case was heard in February amid a wider crackdown on protest movements in Britain and across Europe, as environmental activists have used direct action protests to demand urgent government action against climate change.

Judges David Bean and Timothy Kerr ruled in the group's favour on Tuesday, finding that the regulations granting the new powers were unlawful.

The High Court granted the government permission to appeal and suspended its decision that the new powers should be quashed pending the outcome of the appeal.

Liberty's legal action focused on the Public Order Act, under which the police can impose conditions on a protest if it could cause "serious disruption to the life of the community".

The law was amended last year, so police could impose conditions in cases where a protest could cause "more than minor" disruption, which Liberty said was unlawful.

Government lawyers argued that ministers were given express powers to amend the law on what amounted to serious disruption.

But the High Court ruled that the government exceeded its powers, which "did not extend to lowering the threshold for police intervention".