More than 6 million people in Yemen are on the verge of starvation, Oxfam warned on Tuesday, adding that months of war and a blockade on imports were pushing an additional 25,000 people into hunger every day.

Also on Tuesday, a humanitarian truce has failed to take hold after Saudi-led warplanes resumed strikes against rebels, military sources said. 

One in two of Yemen's people - nearly 13 million - are now struggling to find enough to eat, the aid agency said.

"As the warring parties continue to ignore calls for a ceasefire, the average family in Yemen is left wondering when their next meal will be," Oxfam's Yemen country director Philippe Clerc said.

Nearly 4,000 people have been killed and more than 1.2 million displaced in a conflict between Houthi rebels and forces loyal to exiled President Abdrabbo Mansour Hadi. Four fifths of the population need help, the United Nations says.

Oxfam said the number of hungry people had risen by 2.3 million to 12.9 million since March, when a Saudi-led coalition backing Hadi began bombarding the Houthis and imposed a blockade in a bid to cut off arms supplies.

"In a country that has historically faced food shortages, this is the highest ever recorded number of people living in hunger," Oxfam said in a statement.

It said the blockade had exacerbated the humanitarian crisis in Yemen, which imports up to 90 per cent of its food and the majority of its fuel.

UN humanitarian coordinator for Yemen Johannes van der Klaauw said more than 6 million people were in an emergency food situation - the phase before famine on the internationally used food security scale.

"The food situation in many governorates including Aden is very critical, but we're not at the stage of famine," van der Klaauw added.

"In some governorates the level of criticality is such that the next level would be famine, but we're not there and let's hope we do not get there."

Van der Klaauw, who visited Aden at the weekend, said the United Nations hoped to scale up aid to the port city massively now that fighting had moved north.

Some markets in the city are still functioning, he added.

The Arab coalition announced a five-day truce from late on Sunday to allow in emergency aid, but fighting has continued in some places.

Oxfam said Saada governorate in the north was the worst affected by food shortages, with nearly four in five people going hungry and half at a critical level.

In neighbouring Hajjah governorate families uprooted by the wars are having to sell livestock at well below market value to buy food, Oxfam said. Some displaced families in Sanaa have resorted to begging

The World Health Organization (WHO) said on Tuesday that 3,984 people had died and 19,347 had been injured between March 19 and July 19, according to data from health facilities.

It also recorded an upsurge in cases of dengue fever in Yemen, with nearly 5,700 suspected cases reported since March, around half of them in Aden.

Meanwhile, the five-day truce that began on Monday was unilaterally declared by the pro-government Arab coalition to allow the delivery of desperately needed relief supplies.

The coalition, which mounted an air campaign against the Houthi rebels and their allies in late March, had reserved the right to hit any military movement by the insurgents.

Air strikes targeted rebels north of Aden, Yemen's second city, which was mostly recaptured by loyalists last week after four months of ferocious fighting, military sources said.

Raids also struck rebels in nearby Lahj province, where forces loyal to Hadi have tightened the noose on insurgents in the strategic Al Anad airbase.

Three air raids targeted a rebel convoy near Sabr, north of Aden, where loyalists had advanced over the past days, military sources said.

Other raids hit a building occupied by insurgents in Jaawala -- also north of Aden.

An overnight air strike hit rebels in Marib, east of Sanaa, witnesses said.

Fighting around Aden has left 28 dead since Monday, including 22 rebels, two civilians and two pro-Hadi southern fighters, said city health chief Al Khader Laswar.

On Monday, coalition warplanes hit positions of pro-government forces in Lahj by mistake, killing 12 people and wounding 30 others, military sources and witnesses said.

UN chief Ban Ki-moon on Sunday made a plea for all sides to "agree to and maintain the humanitarian pause for the sake of all the Yemeni people".

The rebels said they were not consulted about the ceasefire.

Source: Timesofoman