WASHINGTON (AFP) - A French woman and her local guide kidnapped in Sanaa were development workers for a project funded by the World Bank in Yemen, the World Bank Group said Tuesday.

In a statement, it said it was "deeply concerned" about the kidnapping - but stressed that neither were directly employed by the Washington-based institution.

The pair were abducted from a taxi in the centre of the Yemeni capital earlier Tuesday by unidentified armed men, according to a Yemeni security source.

Their names have not been disclosed.

"Both individuals are contracted by a consulting firm, which is contracted by the Social Welfare Fund of Yemen under a project funded by the World Bank," its Washington head office said in a statement.

"We hope for their safe return to their families soon."

French President Francois Hollande had stated earlier Tuesday that the 30-year-old French woman worked for the World Bank.

"We are trying to locate her," he said, as he called for her release "as soon as possible."

Yemen has descended into chaos since Shi'ite Huthi militia swept into Sanaa from their mountainous northern stronghold last year.

Since then, France has joined countries such as Saudi Arabia, the United States, Egypt and Germany in shuttering its embassy in Sanaa.