The PP and Vox are negotiating the formation of coalition governments in three regions following those elections - a scenario that could be repeated after a national election next month.

Polls consistently show the PP winning most votes then but requiring an alliance with Vox to be able to form a government.

In Valencia, the two parties reached an agreement in principle that would hand Vox the presidency of the regional parliament, Vox said in a statement.

The PP would lead the regional government and also hold the vice presidency. An official for the PP confirmed the agreement.

The two parties are still in talks in the regions of Extremadura and Aragon, while they will need Vox to agree to abstain from voting for the PP to form minority governments in Cantabria, Murcia and the Balearic Islands.

Prime Minister Pedro Sanchez called a surprise snap election for July 23 after his Socialist party (PSOE) and their junior coalition partners Podemos were routed in the regional and municipal ballots last month.

The election is shaping into a binary choice between those opposed to a government that includes the far-right Vox and those who oppose the current coalition with far-left Podemos.

PP leader Alberto Nunez Feijoo has not ruled out reaching an agreement with Vox to form a national coalition government but has insisted he will try to win a majority. The PP and Vox already govern in coalition since last year in the region of Castilla y Leon.

Vox said the agreement in Valencia was reached based on five key principles which included more support for families and defence of traditional national identity.

Founded in 2013 by former members of the mainstream conservative PP, Vox is anti-Muslim, anti-feminist, socially conservative, economically liberal, and opposes Spain's political system of devolved government.

The PP was ousted from power in a confidence vote in 2018 after Sanchez struck a deal with Podemos and Catalan and Basque nationalist parties.