MOZAMBICAN riot police were called in to rescue 30 senior Concor site managers after they were taken hostage by 400 striking construction workers at the R7,5-billion MOZAL aluminum smelter near Maputo city on Tuesday, African Eye News Service reports. The demonstrators held the group of Mozambican and South African managers hostage for seven hours after a wage dispute flared into open protest. The dispute was sparked by allegations that Concor pays South African workers substantially more than Mozambicans are paid for similar work.