PARIS -- For more than eight decades, Spain has been branded the starting point of the worst plague of the 20th century -- the 1918-1919 influenza pandemic which by some estimates slew as many as 40 million people.

But Spain has been unfairly accused, AFP quotes a group of British scientists as saying.

The dissenters believe "Spanish flu" probably originated in France, where it was born on World War I's western front and then stealthily mutated, becoming a far more efficient killer than any shell, bomb or poison gas.

The great pandemic inspires deep fascination among historians and chilling fear among medical watchdogs, who dread the toll if a similar virus emerged today in the era of jet travel.

Influenza has a cosy image for being an uncomfortable but otherwise innocuous illness, yet this viral strain was a swift and brutal claimer of lives, literally drowning its victims, usually the young and healthy rather than the old and frail, by filling their lungs with their own blood.

"It was 25 times more deadly than ordinary influenzas," says **** New York Times **** writer Gina Kolata in her book on the pandemic, "Flu." "This flu killed 2.5 percent of its victims. Normally, just one-tenth of one percent of people who get the flu die."

But where did this lethal bug come from?

A prevailing view is that it began in a mild yet highly infectious form in February 1918 in the Spanish tourist town of San Sebastian, close to the border with France, where people came from around Europe for a few days to escape the horrors of war.

It then somehow stepped up swiftly to a more pernicious form, according to this view. Its first identified fatality was a 21-year-old American soldier who reported sick at a camp in South Carolina on September 19, 1918, as his unit was preparing to head for France.

Within a few months, other deaths occurred, in places as widespread as Alaska, Australia, Britain, china, India, Nigeria, South Africa and the Norwegian island of Spitzbergen.

For a team of skeptics, led by John Oxford, a professor of microbiology at the Queen Mary University of London, it is impossible for a virus to have spread to such remote places so quickly at a time when people needed weeks or months to travel oceans.

"The disease had spread around the globe before this time," they write in February's issue of **** The Lancet Infectious Diseases ****.

They trawled through modern studies as well as contemporary accounts to see whether the virus had been "seeded" before it became a pandemic.

They believe they have evidence that at least two mini-outbreaks of the killer flu occurred, firstly among British troops in France in 1916 and then in Britain in 1917, but were never properly identified as such.

The victims were misdiagnosed as having pneumonia, "epidemic catarrh" or "purulent bronchitis," they contend.

In 1916, an outbreak occurred in a huge British army base at Etaples, south of the French Channel port of Boulogne, which housed 100,000 troops on any one day and where over a million soldiers stayed while en route from England to the trenches of northern France and Belgium between 1916 and 1918.

Although there is no hard evidence to say that the flu started here, Oxford's team note the base was an ideal breeding ground for a killer virus.

For one thing, it had piggeries to feed the troops and bought poultry from local markets. Pigs and fowl are notorious for being potential vessels for influenza, able to harbor viruses which then mutate into new forms and then pass onto humans in proximity.

The men, too, were housed in tents or temporary wooden huts, which was ideal for spreading a respiratory infection, especially in the stressful conditions of warfare.

Over a couple of years as it passed around the troops, the virus would have undergone "multiple but small mutational changes" in its genes that would have boosted its fatal powers.

After the end of the war in November 1918, demobilization and welcome-home parties simply widened the target, releasing the bug into a civilian population weakened by under-nourishment.

At that point, says Oxford, the virus started reaping so many lives that the world suddenly took notice of it. Indeed, only then was it termed influenza rather than some other sickness.