Hundreds of thousands of Syrian refugees in Jordan are stretching the kingdom's meager water resources "to the limit," two British aid agencies warned on Friday, calling for international help.

"The Syrian refugee emergency is highlighting one of Jordan's most pressing problems -- water," said Christian Snoad of Oxfam, in a joint statement with the British Red Cross.

Human Rights Watch on Thursday urged U.S. President Barack Obama on the eve of his Jordan visit to press King Abdullah II to accept Palestinian refugees and other asylum seekers at the Syrian border.

"Jordan is routinely and unlawfully rejecting Palestinian refugees, single males, and undocumented people seeking asylum at its border with Syria," HRW and Harvard Law School's International Human Rights Clinic said in a statement.

Syrian rebels on Tuesday seized a guard post near the Jordanian border and a tank brigade headquarters in the south of the country, after regime forces withdrew, a watchdog reported.

"They managed to seize control of a border post near Tel Shehab at dawn after regime forces evacuated the post following violent clashes," Rami Abdel Rahman, directer of the Syrian Observatory for Human Rights said.

Lebanon and Jordan are playing with fire by allowing “jihadists” and “weapons” to pass across their borders into Syria, the Syrian government daily al-Thawra warned on Sunday.

"The fire of terrorism will consume not only Syria, but could spread to Lebanon and Jordan, particularly if these two countries intervene in the situation in Syria, ignoring the flow of armed men and weapons from their territory, or by participating directly in the conspiracy against Syria," the newspaper said.

Fourteen Palestinians were killed on Saturday and 32 injured, some seriously, when their bus collided head-on with a truck in Jordan, the emergency services in the kingdom said.

The passengers had been on the way home to the West Bank from Saudi Arabia where they had performed the Muslim minor pilgrimage or omra when the accident happened.

A Syrian security official on Friday accused Jordan of opening its borders to jihadist fighters and allowing weapons bought by Saudi Arabia in Croatia to be smuggled into the country.

"We deplore the change of attitude of Jordan, which in the past 10 days has opened its borders and is allowing to cross over (into Syria) jihadists and Croatian weapons bought by Saudi Arabia," said the source.

Syria's two-year conflict and the refugee crisis that it has triggered are at real risk of exploding across the Middle East, the U.N. refugee agency warned on Friday.

"I believe that if the Syrian conflict goes on and on and on, there is a real risk of an explosion in the Middle East, and then there will be no way to cope with the challenge from the humanitarian, political and security perspective," said U.N. High Commissioner for Refugees Antonio Guterres.

Britain's Prince Charles and his wife Camilla on Wednesday visited a camp for Syrian refugees in northern Jordan as part of a trip to the Middle East, an official said.

The royal couple toured the United Nations-run King Abdullah Park refugee camp near the border with Syria that hosts about 1,000 Syrians who have fled the war in their country, said the Jordanian government official.

Syria's army could go on fighting "for years" rebels trying to overthrown President Bashar Assad, a pro-regime newspaper said on Tuesday, adding however that citizens could join according to their capacities.

"The army is in perfect condition, its soldiers and officers have been fighting for two years with a courage and bravery unparalleled in world history, in the fiercest of battles," said Al-Watan newspaper, as the conflict prepared to enter its third year.

President Barack Obama on Monday, just days ahead of his Mideast trip, met with about 10 leaders of Arab-American groups who encouraged him to deliver a message of hope to the Palestinian people even if he is unable to immediately deliver a peace plan with Israel.

Obama met with the officials Monday, four days after meeting with Jewish leaders as part of his preparation for the visit.