At least four aid workers have been kidnapped in southern Niger by unknown gunmen, their employers say.
Three of those seized are from Niger and work for medical charity Befen – the fourth is a Chadian working for Alert Sante, Reuters new agency says.
An al-Qaeda group operating in both Niger and neighbouring Mali has seized several Westerners in recent years.
Analysts say the rebel takeover of northern Mali has created a security vacuum in the region.
Niger’s government has sent troops and aircraft to search for the aid workers.
They were abducted in the town of Dakoro, where they had been treating malaria and helping malnourished children, the two medical charities said in a joint statement.
Niger, one of the world’s poorest countries, was hit by a severe drought this year, with the government appealing for international help to end food shortages.
While thousands of people have fled to Niger after ethnic Tuareg and Islamist rebels seized northern Mali in April.