An influential grassroots separatist group has joined voices in Catalonia urging the regional president to ignore warnings from Spain's central government and definitively declare independence.

The Assemblea National Catalana, or ANC, has issued a brief statement calling for regional leader Carles Puigdemont to lift a temporary suspension of an ambiguous independence proclamation he made this week.

Puigdemont said that Catalonia was proceeding with independence but proposed freezing its implementation for a few weeks to see if negotiations could be held with Spanish authorities.

The central government responded by threatening to activate constitutional powers to take over Catalonia's self-government.

Adding pressure on Puigdemont, ANC says that "it doesn't make sense to keep the suspension of the independence declaration" given Madrid's rejection of any dialogue.

The ANC is a civil society group that organized massive protests in support of secession.