SANAA - Aid agencies began delivering help to desperate civilians Wednesday as a five-day ceasefire took hold in Yemen after nearly seven weeks of Saudi-led air strikes against Iran-backed rebels.

The five-day humanitarian pause - which began at 11:00 pm (2000 GMT) on Tuesday - is the first break in the air war in support of exiled President Abedrabbo Mansour Hadi since its launch on March 26 and has strong backing from Washington. Hours after it took effect a Saudi defence ministry official said rockets were fired from Yemen’s rebel-held north, hitting the border areas of Jazan and Najran inside the kingdom.

The official said there were no casualties and that Saudi forces had “practised self-restraint as part of their commitment to the humanitarian truce”.

The alleged attack came despite a promise by the Huthi rebels and their allies to abide by the ceasefire. Riyadh has warned it will punish any attempt to exploit the truce. As aid agencies said they were starting to deliver assistance, residents of the rebel-held capital Sanaa told AFP the ceasefire came as a much-needed relief.

“We hope this truce becomes permanent. We finally managed to sleep peacefully last night,” said 25-year-old Mohammed al-Saadi. Saudi Arabia’s King Salman also used the first day of the pause to announce the doubling of the kingdom’s aid commitment to Yemen to some $540 million.

More than 1,500 people have been killed since mid-March in the air campaign and fighting between rebel forces and Hadi loyalists, according to the United Nations.

The Huthi rebels, allied with army units loyal to ex-president Ali Abdullah Saleh, have taken control of large parts of Yemen including Sanaa and were advancing on Hadi’s southern stronghold of Aden when Riyadh launched the air campaign. Saudi Arabia has accused regional rival Iran of arming and funding the rebels, a charge Tehran denies. The weeks since the start of the air war have seen repeated warnings of a dire humanitarian crisis, with shortages of food, water, fuel and medical aid.

UN agencies and private aid groups had been preparing to boost their efforts since the ceasefire was announced last week and on Wednesday began taking steps. A plane carrying medical aid and MSF personnel was expected to arrive in Yemen later Wednesday, she said, with a second aircraft set to follow on Thursday. But the five-day truce is “not sufficient given the needs of the population,” Ingres said, insisting on the need for “permanent access” to all regions affected by the conflict.

Iran has also announced it is sending an aid ship to Yemen, prompting a fresh war of words with Washington.

Iranian Brigadier General Masoud Jazayeri warned the United States against stopping the ship, after Washington said it was tracking its movements.

Jazayeri said that if Saudi Arabia or the United States “continue to create obstacles on Iran’s aid delivery, a fire might start that would definitely be out of their control.”

Meanwhile, a clearer security arrangement between Gulf countries and the United States is critical to fighting terrorism, US Secretary of State John Kerry said on Wednesday, ahead of a summit in Washington with Arab leaders.

US President Barack Obama will meet with Saudi Arabia’s Crown Prince Mohammed bin Nayef and Deputy Crown Prince Mohammed bin Salman in Washington’s Oval Office later, before the summit with the six-nation Gulf Cooperation Council (GCC).

“Defining ... a clearer defence arrangement between the GCC and other friendly countries and the United States is going to be critical to helping to push back against the terrorism, as well as some of the other activities that take place in that region that are unsettling to all of those countries,” Kerry said.

He was speaking to reporters on the sidelines of a meeting of NATO foreign ministers in Antalya, Turkey, before flying back to Washington to attend a dinner at the White House with Obama and GCC officials.

Obama invited the GCC nations - Saudi Arabia, Kuwait, Bahrain, Qatar, the United Arab Emirates and Oman - after six world powers reached a framework agreement with Iran that would give Tehran sanctions relief for reining in its nuclear programme.