The United Nations says it has suspended its humanitarian operations in the stronghold of Yemen’s Houthi rebels after they detained eight more U.N. staffers.

The United Nations has paused all operations in Yemen's Sa'ada region after more U.N. staff were detained by the Houthi authorities, deputy U.N. spokesperson Farhan Haq said on Monday. "This extraordinary and temporary measure seeks to balance the imperative to stay and deliver with the need to have the safety and security of the U.