Raytheon Technologies' top boss warned on Tuesday the U.S. aerospace and defense firm will lose 'several thousand' employees who refused to take COVID-19 vaccines, as it prepares to meet the Biden administrations Jan. 1 deadline for immunization.

"We will lose several thousand people," Raytheon Chief Executive Greg Hayes said in a CNBC interview on Tuesday, adding that staff hiring was underway. The company has a total of 125,000 U.S. employees.

Raytheon, the maker of Tomahawk missiles, last month said it will require all U.S. employees to be fully vaccinated by mid-December, after the Biden administration mandated immunization for nearly all federal employees and contractors, in a bid to increase vaccination coverage in the country. 

Many companies, such as Boeing Co which hold U.S. government contracts, have announced vaccination mandates since then.

Separately, Hayes also said he expects Biden's vaccine mandate to cause "some disruption" in the supply chain in a post-earnings conference call with analysts. 

(Reporting by Kannaki Deka and Vishal Vivek in Bengaluru; Editing by Shinjini Ganguli) ((Kannaki.Deka@thomsonreuters.com;))