The former frontrunner in France's presidential election has been formally summoned for questioning over a deepening scandal involving payments to his wife.

Francois Fillon has been called to face magistrates investigating allegations the politician paid family members for fake parliamentary jobs.

Mr Fillon, who was leading polls until the scandal broke last month, abruptly postponed a high-profile event as investigations continued but refused to step down on Wednesday.

He confirmed he had been summoned for questioning over “Penelopegate” on 15 March, claiming that the investigation process had been unfair and amounted to a “political assassination”.

“I will answer the summons, I will respect the judges…although what we have seen is not natural,” Mr Fillon said.

“I will not cede, I will not give up, I will not withdraw, I will continue to the end because it is democracy that is under attack.”

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Mr Fillon faces a full judicial inquiry into the so-called “Penelopegate” affair but has backtracked from a previous pledge that he would stand down in the event of an official probe being launched.

He has denied wrongdoing, and says his wife was paid hundreds of thousands of euros for genuine work as his parliamentary assistant, though he has acknowledged giving her the work was an error of judgement.

The list of potential charges include misappropriation of public funds, abuse of public funds and influence trafficking.

The former Prime Minister, who is running for the centre-right Républicains, battled down a rebellion by members of his party last month and insisted his withdrawal from the race would destabilise their campaign.