The southern African nation has been battling the spread of the deadly disease since October and has already been forced to delay the start of the new school year.

More than 374 Zambians have died, 12 of them in the past 24 hours, and 9,580 have fallen sick with cholera, an acute form of diarrhea that can kill within hours.

The WHO and the Gavi global vaccine alliance hope to reduce cases worldwide by 90 percent by 2030 through a campaign of vaccination and improved hygiene.

But vaccine doses are in short supply and outbreaks like that in Zambia threaten that goal.

"This outbreak continues to pose a threat to the health security of the nation," Zambia's health minister Sylvia Masebo warned at the announcement.

The minister said the country had received 1.4 million oral cholera vaccines out of the 1.7 million doses already approved by WHO.

WHO, the UN health agency, confirmed the figure for the shipment in a social media post.

Zambia has a population of more than 19 million and adults need two doses for full vaccination, while very young children may need three.

Vaccination will begin in "high-risk areas" around the capital Lusaka, the epicentre of the outbreak with a population of over three million.

At the weekend, Masebo stepped up measures to halt the spread of cholera, including restricting the number of people attending the burial of a death caused by cholera to five.

Last week, President Hakainde Hichilema urged Zambians to take care and to avoid unnecessary travel.

The WHO has expressed concern over the growing number of cholera cases around the world in recent years, with Africa bearing the brunt.

Earlier this month, Zambia's government delayed the start of the new school year by three weeks due to the disease that has spread to almost half of the districts in the country.