SHANGHAI—The U.S. government is working to evacuate American citizens by air from the epidemic-stricken Chinese city of Wuhan as soon as possible, according to people familiar with the effort.

The operation comes as the death toll from a newly identified coronavirus that originated in Wuhan climbs above 40 and the number of confirmed infections tops 1,300, with many of the cases in and around the central Chinese city of 11 million people.

The fast spread of the disease in recent days across China and around the world, including two cases in the U.S., has raised fears of a deadly contagion.

Roughly 1,000 American citizens are thought to be in Wuhan, and the U.S. consulate there is reaching out to those it knows about to offer a seat on the plane, these people familiar with the matter said.

The plane seats around 230 people, and will include diplomats from the U.S. consulate as well as Americans and their families. Those evacuated will be responsible for the cost.