Madrid - Spain's main opposition conservative People's Party (PP) was embroiled in corruption allegations Tuesday, as the party's leadership sought the resignation of one of the accused.

Arturo Gonzalez Panero, Mayor of Boadilla del Monte, near Madrid, is suspected of having bought properties in Miami with illicit money, and has come under increasing pressure to step down.

Four businessmen are in already in custody, and more than 30 other people under investigation, for bribery, influence-peddling and money-laundering in Madrid, Valencia and other locations.

Some of the suspects are former PP officials. Businessman Francisco Correa, who organized PP events, is suspected of being behind a corruption network affecting building permits and lucrative contracts granted by PP municipal councils.

Madrid regional Prime Minister Esperanza Aguirre on Monday sacked two senior party officials over the allegations.

Aguirre herself is under suspicion over reports that her government spied on political rivals in 2008.

The affair comes at a bad time for the PP, making it difficult for the party to focus on attacking Prime Minister Jose Luis Rodriguez Zapatero's ruling socialists over Spain's economic crisis, ahead of the Basque and Galician regional elections on March 1.

PP leader Mariano Rajoy, who has been criticized for weak leadership, has announced an internal investigation into the corruption allegations.

The Madrid regional parliament is also conducting a probe into the spying scandal. Critics claim that the investigation is being controlled by the PP.

But PP spokeswoman Soraya Saenz de Santamaria admitted Tuesday there may be some case to answer.

"When there are many apples in a basket, some of them may not be good, and we have to get them out," Saenz de Santamaria said. (dpa)