Marine Le Pen's anti-immigrant, eurosceptic party has extended its lead in the latest poll on the last day of campaigning.

Official campaigning ended at 12am on Friday with no political activity allowed on Saturday ahead of Sunday's first round of parliamentary elections.

Le Pen's party has led polling since President Emmanuel Macron called a surprise snap election.

One poll, by Les Echos newspaper, suggested the National Rally (RN) could win as much as 37 per cent of the national vote - an increase of two per cent compared to last week.

Macron's centrist bloc Together party was seen reaching 20 per cent.

The New Popular Front leftwing alliance remains unchanged at 28 per cent.

Another poll, by BFM TV and compiled by Elabe, calculated that the RN could see 260-295 seats in the new parliament - potentially crossing the 289-seat bar for an absolute majority.

RN has pledged to boost spending power, reduce immigration and restore law and order.

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The possibility of either of an RN-led government or a hung parliament has unnerved financial markets.

An outright RN victory would set the stage for a challenging "cohabitation" with Macron for the rest of his term until 2027.

Accurate seat predictions are difficult because the final outcome hinges on the second-round results in France’s 577 constituencies.

On Friday, prime minister Gabriel Attal said: "Of course I want to avoid the extremes, especially the far right, being able to win."

After Sunday's first round, rivals to the RN may team up and withdraw candidates in tactical moves to defeat candidates in the July 7 second round.

Analysts suggest that the far-right party has gained from public dissatisfaction with Macron.

While his pro-business reforms have boosted the economy, many voters feel he has neglected their concerns about the cost of living and deteriorating public services.