MADRID — Just as Spain’s financial troubles seemed to be diminishing, Prime Minister Mariano Rajoy has become engulfed in a widening corruption scandal involving payments to the leaders of his Popular Party.

On Thursday, El País, Spain’s leading newspaper, published what it said were excerpts from the party’s financial accounts that showed regular payouts to leading party members above their official salaries. Mr. Rajoy first appeared in the ledgers in 1997 and received sums averaging $34,000 a year through 2008, the newspaper said. The money, it said, came from “donations” from companies, particularly construction companies.

Former party treasurers, including Luis Bárcenas, who has been at the heart of the scandal, are suspected of maintaining the ledgers. Two weeks ago, the Swiss authorities informed Spanish investigators that Mr. Bárcenas had deposited as much as $29 million in Swiss bank accounts. El País, which said it gained access to the Popular Party’s internal accounts from 1990 to 2008, said that Mr. Rajoy declined to comment on its report until internal and external audits ordered by him into the party’s finances were complete. The audits were ordered after news of the Swiss accounts emerged.

But the report is certain to compound the troubles facing his government as it tries to navigate Spain’s economic crisis in a climate of increasing anger and suspicion from the public of all politicians, as scandals related to Spain’s boom years before the 2008 economic collapse come to light in all corners of the country.