UPDATE 1-U.S. government to buy rapid COVID-19 tests from Abbott, Celltrion -official

(Adds additional context and commentary from official)

By Jeff Mason

Sept 21 (Reuters) - The U.S. government has agreed to purchase rapid COVID-19 tests from Abbott Laboratories and Celltrion Inc to ship to nursing homes and other high risk populations as part of President Joe Biden's vaccinate or test plans, a senior administration official said on Tuesday.

The federal government will purchase tests as needed and has agreed to spend up to $626 million in its agreement with Celltrion and $554.4 million in its deal with Abbott, the official said.

The White House announced earlier this month that it will mandate staff at all large employers to either get vaccinated or submit to weekly testing. As part of that announcement, the administration said it would purchase around $2 billion worth of rapid tests.

The U.S. government also has agreements to purchase tests from other manufacturers including Quidel Corp., OraSure Technologies, and Intrivo.

Demand for tests has been spurred in recent months by the emergence of the contagious Delta variant of COVID-19, reopenings of K-12 schools, and an earlier mandate by the White House that will require most U.S. federal employees to either get vaccinated or receive weekly tests.

(Reporting by Jeff Mason and Carl O'Donnell Editing by Chris Reese and Richard Pullin)