US Vice President Kamala Harris and French President Emmanuel Macron on Wednesday agreed on the importance of "absolutely critical" France-US ties, eager to project unity after a diplomatic storm caused by a ditched Australian submarine contract.

Macron was left furious in September when Australia ditched a deal to buy submarines from France in favour of nuclear-powered versions from the US, a deal which had been negotiated in secret.

After weeks of anger in Paris, Macron held face-to-face talks with US President Joe Biden in Rome on October 29.

"I have to say we had a fruitful meeting in Rome a few days ago with President Biden which paved the way for the coming weeks, months and, I have to say, years," Macron told Harris.

Facing each other over a table at the Elysee Palace in the French capital, Macron thanked Harris warmly for her presence for four days in Paris -- a long trip billed as a fence-mending exercise in Washington.

"We do share the view that we are at the beginning of a new era. Our cooperation is absolutely critical for this era," Macron added in English, his voice affected by a sore throat.

The latter comment about "cooperation" was a reminder of France's desire to work closely with the United States on a range of issues from climate change to the Indo-Pacific region, where China's rise is a cause of a mutual concern.

French officials have described their sense of betrayal over the submarine deal, which was termed a "stab in the back" and was seen as a setback for efforts to rebuild ties after years of tension under ex-president Donald Trump.

"I do believe, and we share this belief, that we are at the beginning of a new era which presents us with many challenges but also many opportunities," Harris told Macron, adding that "when France and the United States have worked on challenges and opportunities in the past we have always found great success".

"Building on the great conversation that you and President Biden had, I look forward to the next few days where we'll continue to work together and renew the focus that we have always had on partnership," Harris added.

Harris' trip comes after a huge French-American row that erupted in September
Harris' trip comes after a huge French-American row that erupted in September POOL / Sarahbeth MANEY

Biden had also sought to make amends over the submarine dispute at his meeting with Macron last month, telling the French leader that his government had been "clumsy" in the way it secured the submarines deal with Australia in partnership with Britain.

France temporarily recalled its ambassadors to Washington and Canberra in the wake of the announcement of the deal on September 15.

Anger in Paris stemmed not only from the loss of the deal -- worth Aus$50 billion (31 billion euros, $36.5 billion) in 2016 -- but also the shattering of an alliance that it saw as a cornerstone of its Indo-Pacific security strategy.

Harris is also scheduled to attend a peace forum with other world leaders on Thursday, and an international conference on Libya on Friday.

She said talks with Macron would see them discuss the Covid-19 pandemic, scientific research, space, climate change and the global economy.

During a tour on Tuesday of the famed Pasteur Institute in Paris, where Harris' mother conducted cancer research in the 1980s, the vice-president was asked about the recent difficulties in Franco-American ties.

She compared politics to scientific research, as well as cooking, and suggested it entailed a constant search for improvement.

"There will be glitches and there will be mistakes," she said. "If you don't make the same mistake twice... that's a good process and we should encourage it."

As she arrived on Tuesday, she said she was "looking forward to many, many days of productive discussions reinforcing the strength of our relationship."