Three employees of the International Committee of the Red Cross were kidnapped in Yemen on Monday, a spokeswoman for the Geneva-based humanitarian agency said.
Spokeswoman Dibeh Fakhr said the three ICRC workers were being held in the south of the country but declined to specify their names or nationalities.
"We cannot confirm ... at this stage who is behind (the abduction) or what are the motives. However, we are in touch with the team members and they say they are doing well," Fakhr said by email.
A Yemeni security source earlier said armed tribesmen had kidnapped a Swiss citizen working for the Red Cross in the southern province of Abyan.
The same source said the aid worker was taken from a vehicle in the city of Jaar where he was travelling with Yemeni co-workers and there had been no demands from the tribesmen.
Kidnappings of Westerners in Yemen are mostly carried out by al Qaeda militants or tribesmen.
Lawlessness in the Arabian Peninsula state has alarmed its neighbour and top world oil exporter Saudi Arabia, as well as the United States, which increasingly views Yemen as a front line in its struggle against al Qaeda.
A Swiss woman held for nearly a year in Yemen was freed by her kidnappers and flown to Doha in February following mediation by Qatar. Armed tribesmen had kidnapped the teacher in the western Yemeni city of Hudaida in March 2012 to press the Sanaa government to free jailed relatives, a Yemeni official said.