A boy walks past the spot where two gunmen riding a motorbike shot dead a US citizen who worked as the deputy head of a language school in Yemen's second city of Taiz. -AFP Photo

SANAA: Two gunmen on a motorcycle shot dead early Sunday an American teacher working at a language institute in a central Yemeni city, the region's provincial governor said.

Hamoud al-Sufi said the teacher was shot in his car in Taiz city. He did not have details on who the killers might be, and said an investigation is ongoing.

Much of Yemen saw a collapse of central state authority during the yearlong uprising against longtime leader Ali Abdullah Saleh, who stepped down as president last month.

Militants affiliated with al-Qaida took advantage of the chaos to seize control of towns in the south of the country.

Yemeni security officials said tribesmen kidnapped a Swiss woman working as a researcher in the western city of Hodeida on Tuesday.

Such kidnappings were common even before last year's uprising, with the hostages used as bargaining chips to secure the release of Yemeni prisoners or to get cash and services. Usually in such cases the hostages are released unharmed.

Tribesmen in the area denied the officials' account and said she was taken by militants.