UN High Commissioner for Refugees Antonio Guterres warned on Thursday that regional countries hosting hundreds of thousands of Syrian refugees need "massive" international aid to help them cope with the influx. "Without a much more massive support to the countries in the region, Jordan, Lebanon and others, the international community cannot take for granted that these countries will be able to go on, accepting more and more hundreds of thousands or millions of Syrians refugees," Guterres told reporters in the Jordanian capital Amman. "This is the moment for the international community to fully understand that the support provided to the countries of the region needs to be strongly enhanced, needs to be really massive because there is a risk..." he said. Guterres said the United Nations estimates that more than three million people have fled Syria, mostly to Jordan, Lebanon, Turkey, Iraq and Egypt, since the conflict erupted after a crackdown on protests that began in March 2011 against President Bashar Assad, During his visit, Guterres held talks with Jordan's King Abdullah II, Prime Minister Abdullah Nsur and Foreign Minister Nasser Judeh. The U.N. official called on Jordan "to facilitate the entry of old men and women as well as children and families" fleeing the conflict in Syria, state news agency Petra said. Amnesty International and other world organisations have said that despite statements by Jordanian authorities that the border has remained open to those fleeing the conflict, research indicates that scores are being denied access to the kingdom. The tiny desert kingdom hosts more than 500,000 Syrian refugees, including some 100,000 in the northern Zaatari camp near the border.