A UN expert group on mercenaries on Tuesday urged the United States to exercise stronger official control over private security contractors in Afghanistan. The UN Working Group on the use of mercenaries welcomed a US Senate committee report this month which found that Washington had failed to manage those hired to provide security under contracts worth billions of dollars, with disastrous results. However, the chairman of the UN body, Alexander Nikitin, said..."[...]there should be stronger oversight of United States' private security contractors in Afghanistan and elsewhere"..."The matters discussed in the United States Senate report are too important to be left to self-regulation of companies"...