From Al Jazeera:

A UN official has said that jet fuel for UN aid delivery planes is being blocked by the Saudi-led coalition. The UN operates two humanitarian flights into the capital Sana’a, but there is no jet fuel available for leaving once there and they are having difficulties obtaining permission from the government to transport the needed fuel.

The fuel must be delivered to Sanaa from the port of Aden, which is controlled by the Saudi-backed Yemeni government.

An outbreak of meningitis has also been reported.