Spain's main opposition party came under renewed pressure over a corruption scandal on Tuesday after a judge released a 50,000-page dossier that implicated its former treasurer in the affair.

The files included a police report that alleged Luis Barcenas was involved in the collection of 1.3 million euros (1.7 million dollars) from a network of companies led by people close to the conservative Popular Party.

Barcenas announced last July that he was standing down as the PP's treasurer after he was questioned by a judge over the scandal.

But he remains a member of the Senate and maintains an office at the PP headquarters in Madrid, which pays his lawyer.

Around 70 people, including several PP members, are under investigation in the scandal, in which bribes were allegedly paid for public contracts.

The ruling Socialist Party Tuesday called on PP leader Mariano Rajoy to explain the party's alleged role in the affair.

Rajoy "knows things which seriously affect his party and which have left it literally paralysed," said the Socialist Party's parliamentary spokesman, Jose Antonio Alonso.

Deputy Prime Minister Maria Teresa Fernandez de la Vega called on him to "respond to citizens in order to clearly state his position in rejecting this scourge of corruption."

The PP's parliament spokeswoman, Soraya Saenz de Santamaria, said Tuesday the party would be "the first to withdraw from its ranks anyone who has abused their position."

Rajoy has previously vowed that anyone involved would be held accountable. And last October, he ordered the dismissal of the deputy head of the regional government in the eastern region of Valencia, Ricardo Costa, over the affair.

A court in Valencia last August dropped a corruption probe against the head of the regional government, Francisco Camps, a senior PP member.

Francisco Correa, a businessman and PP event organiser, and Pablo Crespo, a former head of the PP in the northwestern region of Galicia, were arrested in February, 2009 in connection with the case.

Correa allegedly held a number of secret accounts under the name "Don Vito".

The dossier released Tuesday included allegations that he served as an intermediary between real estate companies and PP legislators, handing out gifts that ranged from holidays in Polynesia to tailor-made suits, luxury cars, watches and iPhones in return for public contracts.

The newspaper El Mundo said last week that the PP and the Socialist Party were close to sealing an anti-corruption pact for regional legislators.