French far-right leader Marine Le Pen has denied violating any rules as she and her National Rally party and two dozen others went on trial accused of embezzling European Parliament funds.

Arriving at the court in Paris on Monday, Le Pen said: “We have not violated any political and regulatory rules of the European Parliament”, and vowed to present “extremely serious and extremely solid arguments″ in the trial”.

The case has the potential to derail her political ambitions.

The nine-week trial will be closely watched by Le Pen’s political rivals as she remains a strong contender in the race to succeed Emmanuel Macron when the next presidential election takes place in 2027.

The case comes as a new government dominated by centrists and conservatives just came into office in the wake of June-July legislative elections.

Some observers expect the trial could prevent National Rally legislators including Le Pen herself, from fully playing their opposition role in Parliament as they would be busy focusing on the party’s defence.

Since stepping down as party leader three years ago, Le Pen has sought to position herself as a mainstream candidate capable of appealing to a broader electorate.

Her efforts have paid off, with the party making significant gains in recent elections at both the European and national levels. But a guilty verdict could seriously undermine her bid to take the Elysee.

National Rally and 27 of its top officials are accused of having used money destined for EU parliamentary aides to pay staff who instead did political work for the party between 2004 and 2016, in violation of the 27-nation bloc’s regulations.

National Rally was called National Front at the time.

Le Pen, whose party has softened its anti-EU stance in recent years, denies wrongdoing and claims the case is politically driven.

She said in her defence: “Parliamentary assistants do not work for the Parliament. They are political assistants to elected officials, political by definition.

“You ask me if I can define the tasks I assigned to my assistants; it depends on each person’s skills. Some wrote speeches for me, and some handled logistics and coordination.”

If found guilty, Le Pen and her co-defendants could face up to 10 years in prison and fines of up to one million euro (£834,000) each.

Additional penalties, such as the loss of civil rights or ineligibility to run for office, could also be imposed, a scenario that could hamper, or even destroy, Le Pen’s goal to mount another presidential bid after Mr Macron’s term ends.

Le Pen was runner-up to Mr Macron in the 2017 and 2022 presidential elections.

She served as party president from 2011 to 2021 and now heads the group of RN legislators at the French National Assembly.

Despite her denial, her party has already paid back one million euro to the European Parliament, the Parliament’s lawyer Patrick Maisonneuve said. Of that amount, 330,000 euro were directly linked to Marine Le Pen’s alleged misuse of funds.