GENEVA — United Nations agencies urged Indonesia, Malaysia and Thailand on Tuesday to step up sea rescue operations and stop preventing thousands of desperate migrants from reaching land. An estimated 4,000 men, women and children from Myanmar and Bangladesh are adrift in boats with dwindling supplies, the UN refugee agency (UNHCR) said. Half of them have been stranded on at least five vessels near the Myanmar-Bangladesh coast for more than 40 days, it said. In a joint statement, joined by the International Organization for Migration (IOM), the heads of the UNHCR and UN human rights office called on the three countries to stop trying to push boats away from their territorial waters. Authorities should “provide for effective, predictable disembarkation to a place of safety with adequate and humane reception conditions” and establish screening procedures to identify those in need of international protection as refugees, they added. UN human rights chief Zeid Ra'ad Al Hussein said last week the flow of migrants would continue until Myanmar ended discrimination against its Rohingya Muslim minority. In Myanmar, several hundred people have abandoned their journey and returned to Rakhine state after paying smugglers 200,000-300,000 kyat ($182-$273) for re-entry, UNHCR said on Tuesday, calling for them not to be punished for irregular departure. “Their reports of food shortages, dehydration and violence on board are consistent with reports from arrivals in Thailand, Malaysia and Indonesia,” it said. “Since the weekend, there have been no new reports of landings elsewhere in the region.” A migrant boat pushed back out to sea by southeast Asian nations over the weekend has not been heard from for two days, raising concerns about the fate of 300 people on board, rights groups said on Monday. — Reuters