A fragmented Spanish Parliament has convened for the first time, including five Catalan politicians released from prison for the occasion and escorted there by police.

Four separatists, on trial for Catalonia's 2017 secession attempt, were elected to the Congress of Deputies and one to the Senate last month.

The Supreme Court has allowed them to attend the opening sessions in Madrid but they are likely to be barred from future meetings by the chambers' governing bodies, due to be elected later on Tuesday.

For the first time since dictator Gen. Francisco Franco's death in 1975, 24 far-right lawmakers have also taken seats in the lower house, representing the Vox party.

Prime Minister Pedro Sánchez won the national election but has put off negotiations on governing alliances until after the European ballot on Sunday.