Unidentified gunmen kidnapped a British national in the Yemeni capital of Sanaa on Monday, the second foreigner seized in the Arab country within a week, an interior ministry official told Xinhua.

The British man was snatched on Monday morning in downtown Sanaa, the official said on condition of anonymity, adding that the police are searching the whole city after witnesses reported the plate number of the gunmen's car.

The Briton was the second westerner who was kidnapped in Sanaa in a week. On Friday, tribesmen kidnapped a German national in the Yemeni capital to press for the release by the Yemeni authorities of their two jailed relatives.

Security in the Arab country worsened after political upheaval broke out in 2011 that severely weakened government control. Foreigners are frequently kidnapped by al-Qaida militants or tribesmen who ask for ransoms or the release of their jailed fellows.

Most of the kidnapped have been freed unharmed. Last month, a South African woman was freed from the southern province of Abyan, but a ransom of millions of dollars was demanded for the release of her husband, who was abducted last May.