Several UN staffers have been pulled out of the region as the vampire scare sweeps across the south of the country for safety reasons.
The UN instructed its staff to temporarily “relocate” to the commercial capital Blantyre.
According to reports, since mid-September, vigilantes have slaughtered seven people suspected of trying to obtain and drink human blood as part of magic rituals.
The vampire rumours have forced authorities to impose a night-time curfew, restricting movement to 10 hours from 7:00am (0500 GMT) until 5:00pm (1500 GMT), the Hindustan Times reports.
Four districts in southern parts of the country have been swept by rumours of bloodsucking humans, but Mulanje, which borders Mozambique, is the epicentre of the killings, the report said.
The UN said it had suspended all visits to the affected areas because the “situation is still unstable and volatile”, AFP reports.
“We have instituted an intensive investigation for us to get to the bottom of the matter,” the president said in a statement.
Police told AFP a seventh person was killed by an angry mob on Monday in Thyolo, the president’s home district.
The latest victim, a mentally-retarded man, was found loitering at night in a village and was lynched by vigilantes who suspected he was pretending to be insane, said police spokesperson Lloyd Maida.
According to the UN, Rumours of vampires allegedly originated from Mozambique and “spread across” the borders to the Malawian districts of Mulanje and Phalombe.
The United States embassy has also temporarily withdrawn its team of Peace Corps volunteers from the districts surrounding Mulanje and has advised its citizens not to visit the affected districts, this according to the report.