Spanish Socialist Workers Party, or PSOE, secretary-general and opposition leader Alfredo Perez Rubalcaba on Sunday called on Prime Minister Mariano Rajoy to resign due to the corruption case involving the governing Popular Party regarding alleged clandestine payments to its leaders.

Rajoy is "a burden" and "cannot lead our country at a moment as delicate at this," Rubalcaba said.

The prime minister, "far from being a solution" for Spain's problems "has become one more problem," and therefore "we ask him to leave the post of prime minister," the opposition leader said in a press conference at party headquarters.

What Spain needs now to emerge from its economic recession is a "reliable, strong and trustworthy" government, something that the conservative PP no longer offers, Rubalcaba said.

Rajoy on Saturday denied allegations that he received secret cash payments from the PP 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 pledged that the party would act with the "utmost transparency" to get to the bottom of the matter. EFE