Spain's Prime Minister Mariano Rajoy will on Thursday present a new law aimed at tightening political party accounting rules, the day after his health minister resigned amid a massive corruption scandal.
Health minister Ana Mato stepped down on Wednesday after being linked to the scandal involving an alleged kickback scheme at the heart of the prime minister's conservative Popular Party.
Her departure was accepted by Rajoy whose government has been embarrassed by the court investigation into illegal payments for public contracts, the latest in a string of graft cases that have outraged Spaniards.
"I have decided to present my resignation," Mato said in a statement, adding that she was stepping down for the good of the government and the party.
Mato has not been named as an official suspect in the bribery probe but the investigating judge said earlier Wednesday she had "benefited from" holidays, cash payments and other gifts when she was married to Jesus Sepulveda, a former Popular Party mayor of a Madrid suburb.
The bribes-for-contracts scheme, known as the "Gurtel" case, allegedly extended to six regional Popular Party governments and operated between 1999 and 2009, when the investigation began.
High Court judge Pablo Ruz said he had evidence to try 43 people for corruption, including Sepulveda and three former party treasurers.
Spanish media have reported that businessmen paid for designer goods, first communion celebrations and even clowns and confetti for children's birthday parties for Mato and her daughter in exchange for kickbacks.
Mato could be called to testify in the case.
The 55-year-old was one of the least popular members of Rajoy's government.
She was harshly criticised for her handling of the case of a Spanish nurse who became infected with Ebola after caring for two elderly missionaries who died from the disease at a Madrid hospital.
A spokesman for the opposition Socialist party, which had called for Mato's departure, said her resignation showed she had been lying when she said earlier that all the allegations against her "were false".
The kickback probe is one of a series of damaging graft scandals in Spain that have involved politicians of all political stripes, businesses, football clubs and even the king's sister.
Rajoy has promised reforms to crack down on corruption and at 0900 GMT Thursday is due to announce a new law aimed at tightening political party financial accounting rules.
In 2013, the premier resisted pressure to resign over allegations of undeclared payments to members of his party.
With the country set to go to the polls for a general election in 2015, corruption is the biggest concern for Spaniards after unemployment, according to a recent poll by the Centre for Sociological Investigations.