WASHINGTON - The US Postal Service (USPS) has recently raised concerns over new vaccination rules announced by the federal government.

Compliance "could result in labor challenges and high levels of absenteeism," the 644,000-employee USPS wrote in a financial filing.

Some employees could opt to leave, which "could cause significant business disruptions, and could adversely impact service performance and result in lower mail volume and revenue," it added.

The federal government earlier this month asked companies with 100 or more employees to mandate weekly testing or vaccines by Jan 4, while it required health care workers at facilities participating in Medicare and Medicaid to be fully vaccinated.

The new rules cover 84 million employees in the United States, according to government officials.