Conservative candidate Francois Fillon has vowed to pursue his campaign for the French presidency despite receiving a summons from magistrates investigating allegations he paid his British wife more than €900,000 for a fictitious job.

He labelled the probe as an attempted "political assassination" that had been "biased from the start".

Speculation had been rife that Mr Fillon might withdraw his candidacy after receiving a summons from three judges.

They were handed the case last Friday when a financial prosecutor asked them to launch a probe into whether Penelope Fillon was paid as assistant to her husband and his successor in parliament. She had previously told the Telegraph: "I have never been his assistant."

Speaking from the Paris headquarters of his centre-Right Republicans party and surrounded by senior campaign chiefs, Mr Fillon confirmed he had been summoned on March 15 in view of being placed under formal investigation - one step short of being charged.