(CNN) -- Allegations of high-level corruption in Spain's ruling conservative party followed Prime Minister Mariano Rajoy to Berlin, where on Monday he strongly denied that he or other top conservatives had accepted secretive cash payments from the party for years.
"The things that are attributed to me are false. I can say it again today," Rajoy said at a news conference with German Chancellor Angela Merkel. It was the first time he taken questions from reporters since the Spanish newspaper El Pais published allegations about the payments Thursday.
On Saturday, Rajoy denied the allegations in a speech to his party's top leadership that was televised nationally.
In Berlin, where he and Merkel tried to keep the news conference focused on their bilateral economic talks, Rajoy said he has a "stable" government and an absolute majority in the Spanish parliament. Spain's Socialist opposition leader, Alfredo Perez Rubalcaba, has demanded that Rajoy resign over the scandal.
Rajoy also announced that lawyers for his Popular Party are studying possible lawsuits against those who have made the allegations, leaked the allegations or published the allegations. A statement issued by the party earlier in Madrid said all legal options were on the table, including potential criminal or civil lawsuits.
Merkel said she is confident that Spain and Rajoy will solve Spain's deep economic problems, and she said bilateral talks with Rajoy indicated that Spain has been enacting structural and economic reforms aimed at reactivating the economy.
She added that Germany is well aware of Spain's high level of unemployment -- the rate is 26% -- but she said she is sure the reforms will make an impact.
On Thursday, El Pais published what it said were handwritten documents detailing 19 years of secretive cash payments.
The payments continued through 2009, the newspaper reported, including tens of thousands of dollars paid to Rajoy.
Rajoy, saying he has nothing to hide, announced Saturday that his income tax statements and declaration of personal wealth will be posted this week on the prime minister's website.
"We can't permit that Spaniards, whom we are asking to make sacrifices, could have the impression that we are not up to strictest ethical standards," he said.
El Pais reported that the money came into Popular Party coffers from construction firms and other businesses and was used for various purposes, including secretive cash payments to party officials.
The newspaper reported that the individuals and companies cited in the alleged documents have denied giving or receiving party funds in an off-the-books manner.
El Pais headlined its story Thursday, "The secret papers of Barcenas," referring to a former Popular Party treasurer, Luis Barcenas, who is under investigation for a private Swiss bank account said to hold €22 million.
Rajoy insisted that case "has nothing to do with the Popular Party. The Popular Party does not have, nor has it had, bank accounts in a foreign country."
Also Thursday, another newspaper, ABC, headlined its story: "Luis Barcenas accuses the Popular Party leadership of having collected in B," the letter Spaniards typically mention when referring to secretive cash payments under the table with the aim of avoiding taxes.
The party later Saturday issued an internal report saying that its top leaders, from 1995 to the present, have signed sworn statements or will do so in the coming days that attest they have all paid their taxes properly and have not received any improper cash payments.
Rajoy earlier also ordered an external audit of the party's finances.
He has warned his political adversaries that the party will defend itself and that their efforts to hurt the party and the government will not succeed.
Hundreds of protesters on Thursday and Friday nights demanded Rajoy's resignation in demonstrations near the ruling party's headquarters, guarded by riot police.