The centrist party of French President Emmanuel Macron is on course to win a landslide victory following the first round of parliamentary elections.

Projections show La République en Marche (Republic on the Move) and its MoDem ally set to win up to 445 seats in the 577-seat National Assembly, reported BBC.

The Socialists, France's former ruling party, are seen losing 200 seats.

Traditional parties are urging voters to back Macron's rivals in a run-off vote to avoid him monopolising power.

Macron's party was established just over a year ago and many candidates have little or no political experience. The final outcome will be decided in the second round of voting next Sunday, reported BBC.

Seat projections showed Macron's camp going on to win between 390 and 445 seats in the 577-member National Assembly after next Sunday's second round -- continuing his centrist revolution which has left France's traditional parties in tatters, reported The News International.

Both the Republicans - who had hoped to upstage Macron in the parliamentary election - and the Socialists of Macron's predecessor Francois Hollande appeared set for steep losses.

Marine Le Pen's FN party was left disappointed as she struggles to rebound from her bruising defeat by Macron in the presidential run-off, with the party's result largely unchanged from the first round of the 2012 vote, it stated.

Turnout was markedly down on Sunday compared with the last parliamentary election, reflecting a degree of fatalism among Macron's opponents in the face of his advance as well as a degree of election fatigue, experts said.

Around 49 percent of the electorate cast a ballot -- one of the lowest levels in such an election in decades.

The results showed Macron continuing to impress the French, a month after being elected France's youngest-ever president on May 7, reported The News International.

Since then he has won praise for appointing a balanced cabinet that straddles the left-right divide and taking a leading role inEurope's fight-back against US President Donald Trump's decision to withdraw from a global climate accord.

If the seat projections are confirmed next week he will have a strong mandate to push through the ambitious labour, economic and social reforms he promised on the campaign trail.

Few MPs are expected to be elected outright on Sunday, said the report.

If no candidate wins over 50 per cent, the two top-placed contenders go into the second round - along with any other candidate who garners at least 12.5 percent of registered voters.

More than 50,000 police were on patrol during the vote, with France still jittery after a wave of jihadist attacks across Europe, it added.