Niger has shut all schools in the region around the capital Niamey and launched a campaign to vaccinate children aged 2 to 15 in an effort to halt a meningitis outbreak that has killed at least 85 since January.

Schools will be closed from Wednesday until Monday next week, the government said in a statement, adding that 905 cases of the disease had been recorded, most of them in Niamey and the west of the country.

"A vaccination campaign targeting children will start on Friday April 24," the statement said.

Prime Minister Brigi Raffini said later on state television on Tuesday evening that the West African nation needed some 1.2 million doses of vaccines but could only get half of that by Thursday.

"For the rest of the needed vaccines, we are appealing to all our partners to come to our aid to supplement the stock of vaccine doses we direly need," Raffini said.

Raffini said there was a vaccine availability problem worldwide and manufacturers had almost nothing to use against the new strain of the disease, but hoped production will resume.

The government also said it had received reports of people and some organisations carrying out vaccinations. It warned that these were unlawful and the vaccines could be meant for a different strain of the disease.

In 2010-2011, the uranium and oil-producing country of Niger, one of the world's poorest nations, successfully carried out a campaign to eliminate the "A" strain of the disease.

Meningococcal meningitis infects the thin lining surrounding the brain and spinal cord. It can cause severe brain damage, deafness, epilepsy or necrosis and if untreated is fatal in 50 percent of cases.

Authorities said the current outbreak included the W135, "C" strain and pneumococcal kinds of meningitis.