Yemeni doctors have appealed to the UN to arrange the evacuation of newborn conjoined twin boys who are in urgent need of treatment abroad.
Abdul Khaleq and Abdul Rahim, who are two weeks old, will not survive if they stay in Yemen, where the health system has been ravaged by years of civil war.
The twins are currently at a hospital in the capital Sanaa, which is in the hands of rebel Houthi movement.
Its airport is blockaded by a Saudi-led coalition backing Yemen's government.
Yemen has been devastated by a conflict that escalated in early 2015, when the Houthis seized control of much of the west of the country and forced President Abdrabbuh Mansour Hadi to flee abroad.
At least 6,800 civilians have been killed and 10,700 injured in the war, according to the United Nations. The fighting and a partial blockade by the coalition have also pushed Yemen to the brink of famine and left 16 million people without basic healthcare.
Abdul Khaleq and Abdul Rahim have separate heads, spines, lungs, hearts and digestive systems, but share a liver, as well as two kidneys, two legs and two arms.
The boys need help to breathe are being treated in an incubator at Sanaa's al-Thawra hospital.
Dr Faisal al-Babili, the hospital's head of paediatrics, said his colleagues were unable to carry out basic diagnostic tests, let alone an operation to separate them.
"They need to travel immediately. They will not be able to survive in Yemen under the social, political and economic circumstances in this country," he told Reuters news agency.
Dr Babili said he hoped the UN or another international humanitarian organisation would be able to evacuate the twins on one of their planes.
Sanaa's airport has been closed to commercial traffic since 2015 because the Saudi-led coalition controls Yemen's airspace.
The restrictions have prevented thousands of critically ill patients from travelling abroad to seek treatment unavailable in the country.