Spain's Prime Minister Sanchez set to announce if he's staying or quitting

People march to show support for Spain's PM Sanchez, in Madrid

MADRID (Reuters) - Spain's Prime Minister Pedro Sanchez is set to announce on Monday whether he plans to stay on or quit the premiership, days after saying he was considering resigning.

Supporters in his Spanish Socialist Workers' Party (PSOE) have urged Sanchez to stay since he said last week he was stepping back for a few days to decide his future and would announce his decision on Monday.

He spoke on the same day a court launched a business corruption probe into his wife's private dealings. Sanchez denies the allegations against his wife, Begona Gomez, which he called part of a sustained campaign of mud-slinging against him and his wife by political opponents.

No time has been given yet for when Sanchez will make his decision known on Monday.

He could resign, or carry on as prime minister, or he could submit to a parliamentary vote of confidence and resign only if he lost the vote.

Another option would be to call a snap election on July 21, the earliest day allowed by the constitution.

Thousands of supporters held rallies in Madrid at the weekend calling on Sanchez to stay on.

The prime minister, 52, first came to office in 2018 and secured another term for the Socialists last year as leader of a minority coalition government.

Opposition parties have condemned Sanchez's move.

"Spain does not have a problem, the one who has a judicial problem is Sanchez, his government, his party and his circle. Let them solve it,” Alberto Nunez Feijoo, leader of the conservative People's Party, told a meeting in the eastern city of Tarragona on Saturday.

(Reporting by Graham Keeley; Editing by Frances Kerry)