The UN says it aims to bring its mission to monitor a cease-fire in Syria to full strength by the end of May.

UN Under-Secretary-General for Peacekeeping Operations Hervé Ladsous told reporters Tuesday that 24 monitors of the UN Supervision Mission in Syria are on the ground. He said the UN aims to have 300 there by the end of the month, and it's going to step up the pace over the next two weeks.

However, Ladsous said UN member countries have only provided 150 workers to the mission so far, adding that the Syrian government denied visas to three of them.

He urged both the Syrian government and antigovernment rebels to sincerely abide by the cease-fire agreed to on April 12th, noting neither side has ended their violent acts against each other.