French lawmakers approved Emmanuel Macron's first annual budget with a thumping majority Tuesday, as the president fends off accusations that his spending plans favour the wealthiest.

France's National Assembly backed the 2018 budget by 356 votes in favour with 175 against, and 27 abstentions. 

"We are going to keep our promises and do what we said," vowed Amelie de Montchalin, who leads the MPs from Macron's Republic On The Move (LREM) party on parliament's finance committee.

Leftwing opponents have accused Macron, a former investment banker, of being a "president of the rich" for exonerating financial investments from wealth taxes.

"A government has never given so many gifts to the richest," Communist Party MP Fabien Roussel told parliament Tuesday.

The 39-year-old president, a self-proclaimed centrist who swept to power in May, insists the move will spur investment and says his wider tax cuts will benefit families of all incomes.

He faces a tricky balancing act in lowering taxes while also slashing the deficit.

France is one of the few countries with a deficit above the EU-mandated three percent of GDP, and he sees lowering it as key to earning credibility with European leaders as he urges ambitious EU reforms.

The budget includes some 15 billion euros ($17.6 billion) of spending cuts, though these, like his tax cuts, are lower than originally planned.

The budget puts a freeze on major infrastructure projects, while nearly 1,600 civil service jobs will be axed.

Macron's reforms to the wealth tax, which will now only be applicable to property, will cost an estimated three billion euros in lost revenue.

He insists it will halt the capital flight seen under his tax-happy Socialist predecessor Francois Hollande.

LREM lawmakers unanimously backed the budget, while Socialist, communist and hard-left France Unbowed MPs voted against it, as did most Republican MPs.

The package, which follows an interim budget for 2017 passed shortly after Macron was elected, will now move to the Senate for approval.

Macron has made structural reforms a key priority in his campaign to boost economic growth -- which currently stands at 1.7 percent -- and lower stubbornly high unemployment of 9.5 percent. 

One of his first moves as president was to push through reforms designed to simplify France's famously complex labour code