Five foreign demining specialists were killed Sunday in an accidental blast while performing their duties in Yemen, said the MASAM Demining Project on Monday. The specialists were transporting mines and explosives to be destroyed, it said, identifying the victims as two South Africans, a Croatian, a Bosnian and a Kosovar. They were transporting the explosives from the central Marib province to a remote location where it could be safely detonated. It said a British national was wounded. The project, part of the Saudi King Salman Humanitarian Aid and Relief Center, began last year and seeks to remove unexploded ordnance from Yemen. MASAM said the experts "lost their lives while attempting to bring safety and security to the Yemeni people, and their service to mankind will not be forgotten." The Iran-backed Houthi militias have planted thousands of mines in Yemen, compounding the suffering of the people, who already have to contend with the militias oppression. UN envoy Martin Griffiths meanwhile arrived in the capital, Sanaa, on an unannounced visit on Monday to discuss the situation in and around the coastal city of Hodeidah, where Yemens warring parties agreed to a ceasefire last month, Yemeni security officials said. The two sides also agreed to a prisoner exchange last month that has yet to take place.