WASHINGTON, Dec. 24 (Reuters) - The Biden administration will lift travel restrictions on eight southern African countries imposed last month over concerns about the fast-spreading COVID-19 Omicron variant, the White House said on Friday (Dec 24).

Foreign nationals who are barred from the United States because they have been in one of the eight countries within the prior 14 days will again be allowed on US-bound flights leaving after 12:01am ET (1.01pm, Singapore time) on Dec 31, a senior official said, confirming a Reuters report.

The United States on Nov 29 barred nearly all non-US citizens who had recently been in South Africa, Botswana, Zimbabwe, Namibia, Lesotho, Eswatini, Mozambique and Malawi in an "abundance of caution" over the variant detected in South Africa.

White House spokesman Kevin Munoz tweeted that Biden "will lift the temporary travel restrictions on Southern Africa countries" effective Dec 31.

He said the decision was recommended by the Centers for Disease Control and Prevention (CDC).

"The restrictions gave us time to understand Omicron and we know our existing vaccines work against Omicron, (especially) boosted," Munoz tweeted.

Reuters reported earlier US public health agencies had recommended lifting the travel restrictions because retaining them would have not a significant impact on US cases given the widespread current US transmission, confidence that an Omicron-specific vaccine would not be necessary and that existing vaccines and booster shots are highly effective.

"This travel pause has served its purpose. It bought time to understand the science, it gave time to analyse the variant," the official, who did not want to be identified because the decision has not yet been made public, told Reuters.

"This was not meant to keep Omicron out. We knew we couldn't do that. The point was to reduce the number of cases coming in - in those early days and weeks."

The restrictions have not prevented flights or Americans from returning from southern Africa.

Top infectious disease expert Dr Anthony Fauci said on Monday that lifting the restrictions was likely "because we have enough infection in our own country ... We're letting in people from other countries that have as much or more infection than the southern African countries."

The official emphasiaed the restrictions were meant to be temporary and lifting them after about a month "sends a pretty clear signal that there's not going to be a significant penalty" for coming forward to disclose new variant information.

The United States had only lifted travel restrictions on South Africa on Nov 8 put in place since late January to address COVID-19 concerns.

In the wake of Omicron, the United States tightened testing rules for international travellers and extended a requirement to wear masks on airplanes and at airports through Mar 18.

On Dec 6, CDC toughened testing rules for international air travellers arriving in the United States, requiring them to obtain a negative COVID-19 test within one day of travel.

Under prior rules, vaccinated international air travellers could present a negative test result obtained within three days of their day of departure.

CDC last week started distributing free COVID-19 home test kits to international travellers at several airports. The CDC encourages - but does not mandate - international air travellers to get a new COVID-19 test three to five days after arriving in the United States.

The CDC last month ordered airlines to disclose passenger names and other information about those who have recently been in the eight southern African countries.