France's most censored filmmaker cuts a perversely wholesome figure in person. Ruddy-faced, with a faded sailor's cap planted firmly on his head, René Vautier looks as if he has just stepped off a boat after facing down a stiff breeze.

As we sit down, the self-styled "petit Breton", who grew up in "the kind of place tourists would call 'not very civilised'", takes stock of his surroundings. We are in a bistro lined with photographs, opposite La Gare Montparnasse. "Writers' haunt," comments Vautier, without much enthusiasm.

A life-long communist, Vautier has always had a utilitarian view of art. This might suggest a dour conversationalist, but not a bit of it. Now 80, Vautier limns his life story with vigour, performing impressions and quoting lines from favourite poets such as Paul Éluard, even breaking into song at one point. And it is quite a story. In the course of a career spanning 60 years, almost as many countries and more than 100 films, Vautier has been shot at and thrown in prison; he almost died on a hunger strike and had kilometres of film footage destroyed. He was back in the news recently when Afrique 50, a tough-talking anti-colonialist documentary he shot nearly 60 years ago, was finally allowed a showing on French television. This month the same film gets its first official UK screening, as part of Tate Modern's Paradise Now! series showcasing French avant-garde cinema from 1890 to the present day.

Vautier is also the hero of a popular French comic book by Kris and Etienne Davodeau called Un Homme est Mort ("A Man is Dead"), after the Éluard poem of the same name. The book, published last year, revisits a short film Vautier made not long after Afrique 50, about a docker shot dead by police in the city of Brest in 1950.

Vautier is slightly bemused but no less pleased by the belated recognition. For a ciné-aste whose films have rarely been granted a certificate to be screened publicly, there is the satisfaction of seeing that his documentaries "can still bear witness after human beings have perished". This is the case with one of Vautier's earliest shorts, another underground film called La Grande Lutte des Mineurs ("The Great Struggle of the Miners"), made in 1948. Seventeen of the miners who appeared in Vautier's original documentary, all now in their 80s and 90s, are at the centre of a major court case, which is taking place now because in France police reports can only be made public after a 60-year wait. The miners are claiming substantial compensation, alleging that they were wrongfully dismissed after holding a sit-in.

"The advantage of being 80 is you finally get the chance to see certain things come out into the open," says Vautier. "The kind of films I've always tried to make are ones of social intervention; the best example is probably Afrique 50."

The story of Vautier's making Afrique 50 would make a good film of its own. "It was 1949 and I'd come top of my class at L'IDHEC [the famous film school in Paris, now known as La Fémis]," says Vautier. "I was offered the chance to make a film for La Ligue de L'Enseignement [France's main education confederation] about colonialism. My instructions were: go and film what you see, what you know and what is true. That is exactly what I did."

Only 21 at the time, Vautier set off for western Africa, travelling extensively in the Ivory Coast (now Côte d'Ivoire), Ghana (then the Gold Coast), Mali and Burkina Faso (then Upper Volta). His trip, which was supposed to last two months, ended up taking up a year. During this time he filled 50 reels of 16mm film, each three minutes long.

After a series of adventures, each one more rocambolesque than the last, Vautier arrived back in France with the makings of a film that showed a very different picture from the official view of colonialism.

The police immediately confiscated all Vautier's footage, but just before it was about to be destroyed, Vautier managed to switch 17 of the original reels with empty ones.

He edited down the remaining reels into a 17-minute film. "There were some things that I absolutely didn't want to show," says Vautier. "For instance, I went to a village one day and was shown the insides of several graves where some Africans had been killed only days before. French cartridges lay scattered on the ground. I just didn't want to use it."

What remains is, says Vautier proudly, "the first anti-colonialist French film to be condemned for being anti-colonialist". Vautier copped 13 indictments and a year in jail. So how does he explain the film's belated rehabilitation?

"In 1995 I received a letter from the foreign affairs minister, saying that he'd like to present me with a copy of Afrique 50," says Vautier.

"He described it as both a 'courageous' and 'necessary' film which shows that from 1950 onwards there was a considerable anti-colonial element in France, particularly among young people."

Ever since he joined the French resistance in 1943 as a 15-year-old, Vautier has grown accustomed to this kind of paradoxical treatment. It was during the war, as part of the Maquis fighting in his native Brittany, that Vautier became a pacifist.

"It was when I threw a grenade at a bunch of Germans and saw what damage it did," he says. "We were nothing more than a bunch of boy scouts. The oldest was 20 and I found myself the standard bearer."

Today, home for Vautier is a small port called Cancale, not far from where he was born in Camaret-sur-Mer, and where his father first took him out to sea as a child. The day we meet he is stopping off in Paris on his way to a film festival in Switzerland. On the table in front of him is a pile of yellowing newspaper cuttings which bear testimony to a career lived on the fringes of the film world.

"A man's place in a powerful country like France is to be with the weakest," says Vautier. "In other words, with the opposition." This belief led to Vautier making several striking films about Algeria's fight for independence from France, including Avoir 20 Ans dans les Aurès ("To be 20 in the Aurès") which won the FIPRESCI prize at the Cannes festival in 1972.

"I wanted to show images that could provoke a discussion, that people in France could see for themselves, that French soldiers were being killed in Algeria," says Vautier. "The only way for a war to stop is if this kind of discussion takes place."

Even today, Vautier has a piece of metal camera lodged in his skull after he was fired upon by French soldiers, hence his nickname ."The Man with the Camera in his Head".

Vautier's principal concern is that his time is running out. He still wants to make at least one more film "about censorship and the necessity to liberate images". There's also his legacy to take care of. That, however, seems to be in good hands. "I recently celebrated my 80th birthday at the same time as my daughter turned 30," says Vautier. "For her birthday she showed me a film she made on the streets of Bogotá about street musicians opposing the government. I have to say I didn't train her, she trained herself." It must be in the blood.

Paradise Now! Essential Avant-garde Cinema, 1890-2008 is at Tate Modern until May 2. Tel: +44 (0)20-7887 8888