"Despite multiple requests made for all parties to facilitate movements, IOM continues to experience challenges evacuating third country nationals from Yemen," Joel Millman told reporters.
The intergovernmental organization's press officer said IOM has received at least 16,000 requests.
The last IOM humanitarian aircraft departed Yemen Sunday with nearly 140 people on board. The organization carried out two other charter flights on April 12 and April 14.
Earlier in the day, a source from the Russian embassy in Yemen disclosed plans to evacuate over 400 Russians and other nationals Wednesday morning.
On Monday, a massive coalition airstrike on a Sanaa military base killed 38 and wounded over 500.
In total, over 700 people have been killed and 2,700 wounded, most of them civilians, since the start of the Saudi-led campaign in Yemen.
