PARIS  - French presidential candidate Dominique de Villepin will offer testimony as part of an investigation into illegal campaign financing in the 1995 election, a case which has put President Nicolas Sarkozy, then budget minister, under intense scrutiny.

Villepin told Canal+ television he would speak to an investigating judge on Monday in the case which aims to determine whether illegal kickbacks from arms sales in Pakistan were used to fund the presidential bid of Edouard Balladur.

Sarkozy, who worked as Balladur’s campaign spokesman, has repeatedly denied any involvement in illegal campaign financing and is immune from prosecution until the end of his presidential term next May.

But Villepin’s testimony, less than four months before the first round of the presidential election, will create an awkward diversion from campaigning as Sarkozy tries to make up his opinion poll lag behind Socialist front-runner Francois Hollande.

“It’s (the testimony) on Monday and I am very pleased for the chance to contribute to the truth,” Villepin said.

A former prime minister and independent candidate in the presidential race, Villepin was chief of cabinet to former president Jacques Chirac in 1995 when Balladur was knocked out of the election, opening the way for Chirac’s election.

The race deepened a personal rivalry between Villepin and Sarkozy, which reached a peak in 2008 during the so-called “Clearstream” affair and became a mainstay of French political life, getting silver screen treatment last year in a movie about Sarkozy’s rise to power.

The left-leaning Liberation daily published an article on Monday entitled “Sarkozy knew”. It cited legal documents in which a former defence ministry official, Gerard-Philippe Menayas, says Sarkozy must have known that illegal kickbacks were used to fund campaigning because the latter was budget minister at the time.

Investigating judge Renaud Van Ruymbeke is exploring a link between the kickbacks, allegedly obtained from sales of submarines to Pakistan, and a 2002 bomb attack in Karachi in which 11 French workers were killed.

The investigation seeks to determine whether the attack came in reprisal for a decision by Chirac to halt the practice of taking commissions from arms sales.

Nicolas Bazire, a friend of Sarkozy and former chief of staff for Balladur, was arrested last September over his suspected role in handling kickbacks and Thierry Gaubert, an aide to Sarkozy, was placed under investigation.