Smoke billows following an air-strike by Saudi-led coalition on a Houthi-controlled army camp on May 12, 2015, in the capital Sanaa. (AFP)
The Saudi-led coalition bombing Yemen today blamed ceasefire violations by rebels for the resumption of air strikes against them.
"They did not respect the humanitarian pause. That's why we do what is necessary to be done," Brigadier General Ahmed al-Assiri told AFP.
"There is an operation in process."
The Arab-dominated coalition resumed the bombing an hour after the five-day truce ended at 2000 GMT on Sunday.
The pause was proposed by Saudi Arabia to allow urgently needed humanitarian aid into Yemen.
"These militia did not stop their fighting. They continued to attack borders, to attack cities in Yemen," Assiri said, adding there was "a very big change on the ground" during the pause.
He accused the rebels of moving missiles with a range of about 70 kilometres (43 miles) towards the border with Saudi Arabia, said there was shelling "every day" of the Saudi boundary zone, and the rebels "hijacked" food and fuel aid in Yemen.
The coalition has been bombing the Iran-backed Shiite Houthi rebels since late March, in an attempt to stop their advance after they seized the capital Sanaa and swept across many other regions.
Analysts say the air strikes have failed to push back the Houthis.
Asked about the possibility of another truce, Assiri said: "When we talk about ceasefire it should be a negotiation between two parties but those militia, since 2216, reject everything."
He was referring to a UN Security Council resolution which in April imposed an arms embargo on the rebels and demanded they relinquish seized territory.