KANO, Nigeria (Reuters) - An epidemic of meningitis and measles has swept through the northern Nigerian city of Kano, killing at least 200 children, health officials said on Monday.

International aid workers said Nigerian authorities had declared Kano, the biggest city in the north, an epidemic zone but there was no official confirmation of this.

A doctor at the Aishatu Bayero Children's Clinic in Kano said 200 children had died in the past two weeks of measles and cerebrospinal meningitis. More than 100 new cases were being reported each day.

``The situation is so bad,'' said the doctor, who spoke on the condition of anonymity. ``We are battling to save these children's lives. This is the worst I've seen since I became a medical doctor.''

International medical charity Medecins Sans Frontieres (MSF) said the federal government had officially declared the epidemic in Kano, but he could not immediately say how many children had died.

``There is an epidemic,'' MSF country manager in Nigeria, Andrew Cunningham, told Reuters in Lagos.

``It's been a very high fatality rate. It's been declared an epidemic by the ministry of health,'' he said.

``There have been more and more cases every week, we're not at the peak yet. It will be another few weeks before we see the worst,'' added Cunningham, who said MSF was working with local clinics to contain the outbreak.

Kano is in the extreme north of Nigeria where outbreaks of meningitis are common during the dry season because of the intense heat. Meningitis causes an inflammation of the brain's membrane and is a common killer in the Sahel region of Africa bordering the Sahara Desert.

The Nigerian government is investigating reports of the deaths of about a dozen children in Kano when international pharmaceutical companies allegedly used experimental drugs during a 1996 meningitis epidemic.

Following the latest outbreak, Health Ministry officials in Kano are encouraging parents to sleep outside with their children rather than in overcrowded rooms.