Spanish Prime Minister Mariano Rajoy on Saturday denied allegations that he received secret cash payments from the ruling conservative Popular Party and said he will release his income statements next week to clear up any doubts.

"I've never received nor distributed 'black money,' in this party or anywhere else," the premier said during an extraordinary PP meeting held in the wake of media reports about an alleged secret ledger showing two decades of off-the-books cash payments to party leaders, including Rajoy.

The prime minister added that those who think he can be "harassed" out of office are "mistaken."

The remarks were Rajoy's first public comments on the allegations since Spanish daily El Pais on Thursday published images of extracts from a purported secret ledger attributed to former PP treasurers Alvaro Lapuerta and Luis Barcenas and covering the period 1990-2009.

The premier acknowledged that the media reports have created a "giant scandal."

But he questioned where the images of the handwritten accounts came from and said whoever had put the "lies" into circulation was trying to create "a state of anxiety and instability in a difficult moment," alluding to the country's deep recession and unemployment rate of more than 26 percent.

He pledged that the party would act with the "utmost transparency" to get to the bottom of the matter.

The controversy picked up steam last month when authorities in Switzerland told a Spanish judge probing a kickbacks-for-contracts scandal known as the "Gürtel case" that Barcenas had deposited some 22 million euros (roughly $30 million) in Swiss bank accounts.

After initially ordering an internal review of PP finances, Rajoy said Jan. 21 that he had commissioned an examination by independent external auditors. EFE