The head of the Catalonia region has called on Spanish Prime Minister Pedro Sanchez to agree within a month on a self-determination mechanism for the region or his party would withdraw backing for Mr Sanchez in the national parliament.

"If there is no agreed mechanism by November, then the pro-independence parties will no longer guarantee stability in the Spanish parliament to Pedro Sanchez," Quim Torra told the Catalan regional parliament.

The Catalan parliament has also voted to reject a Spanish Supreme Court ruling that suspended former Catalan leader Carles Puigdemont and five other pro-independence politicians from public office, marking a new standoff with Madrid.

The assembly backed a motion allowing all six parliament members, who have either fled Spain or are in jail, to delegate their voting rights to a party member, a spokesman for the Catalan parliament said.

In July, Spain's Supreme Court effectively stripped Mr Puigdemont and the other separatist politicians of their public duties due to their role in organising an independence referendum on 1 October 2017.

The moves by the Catalan assembly come a day after riot police charged in to break up a demonstration in front of the parliament building after thousands marched in Barcelona to mark the first anniversary of the referendum.

Madrid imposed direct rule on Catalonia after the referendum, which it branded as unconstitutional.

It then called fresh regional elections in December in a bid to curb the independence movement, but the plan backfired and the secessionists retained a slim majority in the Catalan assembly.

Opinion polls in Catalonia show a relatively even split between those who favour remaining in Spain and those wanting to secede.

Mr Sanchez has said he favours dialogue on Catalonia's future but has ruled out any moves towards independence.