Francisco Álvarez-Cascos and Javier Arenas, both ex-Secretary Generals of the PP, also said they had not received any under-the-table payments. 

They told the court that ex-PP treasurers Luis Bárcenas and Álvaro Lapuerta would be responsible for any alleged illegal financing of the party that may have taken place.

In July, Bárcenas told Spain's High Court he had operated an illegal slush fund for the PP during his time in office.

The former treasurer said he had handed €25,000 ($33,000) in 500-euro notes to Spanish Prime Minister Mariano Rajoy in March 2010.

This has been strongly denied by the Spanish leader, and the PP has distanced itself from the disgraced official, currently being in held without bail in relation to another corruption case.

But further proof of the existence of the slush fund appeared to come to light on Tuesday when Bárcenas' successor told the court he had received two "payments" from the official.    

Cristóbal Páez, the general manager of the PP from July 2009 to April 2010, told the court he had received two payments from ex-party treasurer Luis Bárcenas in 2008.

Both of these were for the amount of €6,000 ($7950), Spain's ABC newspaper reported on Tuesday.

Páez also confirmed that the payments were featured in documents dubbed 'the Bárcenas papers' by the Spanish press.

These papers, initially published in Spain's El País newspaper, allegedly provide evidence of the illegal PP slush fund.

The documents allegedly show that Cascos received €421,693 in illegal funds from 1990 to 2004 while Arenas received €234,320 between 1990 and 20011, according to figures published by El País on Wednesdayy.

The current PP Secretary General María Dolores de Cospedal will testify in court on Wednesday in a highly-anticipated appearance.