(Adds details and background)
SANAA, March 25 (Reuters) - Gunmen kidnapped a married Western couple working at the United Nations office in the Hada district of Yemen's capital Sanaa, where many diplomatic missions are located, a local police source said on Tuesday.
The source gave no further details.
Kidnapping is common in U.S.-allied Yemen, where the government is struggling to contain an insurgency from Islamists linked to al Qaeda, a southern separatist movement, fighting in the country's north, and sporadic conflicts with armed tribes.
Hostage-taking is sometimes carried out by militants aiming to intimidate Westerners, but is also used as a tactic by tribesmen to resolve disputes with the government, and by opportunists hoping to sell hostages on to other groups.
Three foreigners, including a Czech doctor, a British oil worker and a German were seized in February.
Yemen, which borders oil giant Saudi Arabia, has long wrestled with instability, internal conflicts and poor governance.
The United States, along with some other Western and Gulf countries, is working with an interim government to effect a political transition after former president Ali Abdullah Saleh was forced from office in 2012 by street protests.
(Reporting By Mohammed Ghobari; Writing by Angus McDowall; Editing by Robin Pomeroy, John Stonestreet)