White House officials have told U.S. airlines the Trump administration is considering suspending flights from China to the U.S. amid an escalating outbreak of a new coronavirus that has infected thousands of people across the world, people familiar with the matter said.

The Trump administration is looking at a variety of measures to contain the fast-spreading virus, U.S. health officials told reporters on a conference call Tuesday.

White House officials called executives at major U.S. carriers on Tuesday, telling them that a temporary ban on China flights is on the table, according to people familiar with those conversations.

As of Tuesday evening, the Trump administration had not taken that step and there was no guarantee that it would do so.

Two of the people said the White House told them it doesn't immediately plan to ban China air travel, but administration officials are constantly evaluating the situation.

United Airlines, which has the most service of the U.S. airlines to Hong Kong and mainland China with about a dozen daily flights, on Tuesday announced it would cancel dozens of flights next month to Hong Kong and mainland China as the outbreak worsens. The Chicago-based airline said it has experienced a "significant decline in demand for travel to China." United and its rivals Delta and American are waiving cancellation and change fees for travelers booked to China.

The restrictions could affect flights into and out of China, as well as airports across the United States, administration officials said. They declined to be named because no final decision has been made.

A senior staff meeting was held at the White House on Monday during which the restrictions were discussed.

Coronavirus live updates: Outbreak has killed 106 people and infected nearly 4,700

The Centers for Disease Control and Prevention expanded its China travel warning Tuesday, now cautioning all U.S. travelers to avoid the entire country.

Previously, the health agency had advised against nonessential travel to the city of Wuhan, the epicenter of the outbreak.

The Department of Health and Human Services said the CDC is expanding screening for the virus from five to 20 U.S. airports. When asked about the potential for additional travel restrictions, HHS Secretary Alex Azar said "it's important to not take anything off the table."