Catalonia's vice-president has said Spanish authorities are giving the region "no other option" but to push ahead with proclaiming a new republic.

Oriol Junqueras said his party - one of two in the ruling pro-independence Catalan coalition - is "going to work towards building a republic, because we understand that there is a democratic mandate to establish such a republic".

He said he was speaking on behalf of his Republican Left party and not for the regional government of President Carles Puigdemont.

His remarks come amid frantic jockeying in the Catalan government on how to respond to plans by Madrid to fire them and directly manage the region's affairs.

Political representatives for Puigdemont say he does not plan to appear before the Spanish Senate to defend his push for independence and to argue against the central government's move to sack him and his ministers.

Regional party officials said Catalonia's parliament speaker informed their representatives that Puigdemont would instead attend the regional body's session to press forward with a push for independence.

Catalan media also strongly criticised plans by the Spanish government to take control of the outlets as part of moves to invoke constitutional authority over Catalonia.

A joint statement by TV3, Catalunya Radio and the news agency ACN described the plan as "a direct attack on the citizens of Catalonia".

The statement, read out in six languages by television and radio anchors during a news conference, said Catalan public media was highly trusted and rated, and Madrid's threat to take control was "a denial of the right to true, objective, pluralistic, balanced information".

Prime minister Mariano Rajoy is seeking to invoke constitutional authority over Catalonia, with Spain's Senate expected to approve the measures on Friday.

He said the government's plans to take unprecedented control of Catalonia's key affairs and halt the region's push for independence are "exceptional" and he hopes they will not last long.