A United Nations convention banning the use of cluster munitions will take effect in August after being ratified by a 30th country, the U.N. said. "The Secretary-General welcomes this major advance on the global disarmament agenda, and notes that the Convention's entry into force just two years after its adoption demonstrates the world's collective revulsion at the impact of these terrible weapons," Ban's spokeswoman Marie Okabe said on Wednesday at a regular daily briefing. "Cluster munitions are unreliable and inaccurate. During conflict and long after it has ended, they maim and kill scores of civilians, including many children. They impair post-conflict recovery by making roads and land inaccessible to farmers and aid workers," she added. Burkina Faso and Moldova were the 29th and 30th countries to sign on for ratification after the Convention was opened for signature in Oslo in December 2008. Cluster bombs open in mid air and scatter hundreds of smaller explosives, many of which fail to explode and can kill or maim long after a conflict has ended. More than a quarter of the victims of cluster bombs are children who often mistake the brightly colored bomblets for toys.