Updated

Catalan lawmakers are voting on a bill that will allow regional authorities to officially call an Oct. 1 referendum on a split from Spain, making concrete a years-long defiance of central authorities, who see the vote as illegal.

The so-called referendum bill was included at the last minute in the agenda of Wednesday's plenary meeting of the regional parliament, and is likely to be passed by a pro-independence majority later in the day, paving the way to formalize plans for the ballot.

The vote is not recognized by the Spanish government and most political parties at the national level. Prime Minister Mariano Rajoy has vowed to use all legal measures to ensure that it doesn't take place.

Catalonia is a prosperous region in northeastern Spain that already enjoys ample self-government.