(Reuters) - Four Democratic U.S. senators on Friday expressed concern in a letter to Amazon.com Inc Chief Executive Jeff Bezos that the world’s largest online retailer has not given enough support to warehouse staff during the coronavirus outbreak, according to a copy of the message seen by Reuters.

FILE PHOTO: Founder, Chairman, CEO and President of Amazon Jeff Bezos speaks during an event about Blue Origin's space exploration plans in Washington, U.S., May 9, 2019. REUTERS/Clodagh Kilcoyne

The lawmakers, led by Cory Booker and including presidential candidate Bernie Sanders, pointed to a news report that said disinfectant wipes and sanitizers were in low supply at Amazon facilities. The letter said workers risked poor performance ratings if they took sufficient time to wash their hands after coughing or sneezing on the job, also citing a news report.

“Any failure of Amazon to keep its workers safe does not just put their employees at risk, it puts the entire country at risk,” the letter said, noting the virus could survive up to 24 hours on cardboard such as Amazon packaging, according to media.

Amazon said the allegations about its practices “are simply unfounded.”

The senators’ letter reflects the intense pressure Amazon is under to keep warehouses, workers and the public safe while it delivers goods to consumers around the world, some of whom are under lockdown. It also reflects ongoing tensions between a company whose chief is the world’s richest person and Democrats who have long criticized its working conditions and pay.

The other signatories were Senators Robert Menendez and Sherrod Brown.

Seattle-based Amazon has seen a rush of business as a result of the coronavirus outbreak. Earlier this week it said it would receive only vital supplies at its U.S. and UK and other European warehouses until April 5, in order to free up inventory space for medical and household goods in high demand.

Amazon said it was helping communities in need while protecting its staff. It has staggered work times, ended stand-up meetings during shifts and required hand-washing after someone sneezes or coughs. Employees have allotted time to wash their hands whenever they desire, without hurting their performance, the company said.

“We have taken extreme measures to keep people safe, tripling down on deep cleaning, procuring safety supplies that are available, and changing processes to ensure those in our buildings are keeping safe distances,” Amazon said.

The senators’ letter asked the company to answer several questions in writing by March 26, including whether it would agree to cover employees’ COVID-19 test costs and whether it would offer paid sick leave to workers who are not diagnosed with the virus.

The company has announced other benefits for employees fearful of contagion, such as unlimited unpaid time off for hourly workers through the end of March.

The coronavirus has led to at least 11,311 deaths globally, largely in Italy and China. There have been employees at Amazon’s headquarters who have contracted the disease, as well as employees in Europe, where more than 200 workers staged a strike on Wednesday calling for the closure of a shipping center in Saran, south of Paris.

Amazon said this week it was closing a New York City delivery station for a period of cleaning after a worker there tested positive for the virus. The senators asked if Amazon would pledge similar temporary shutdowns should the same circumstance arise at facilities in the future.

One of the biggest U.S. employers, Amazon has opened more than 500,000 full- and part-time jobs in the country, many of them for fulfillment and delivery roles. It said this week it would hire 100,000 more U.S. warehouse and delivery workers to deal with the surge in online orders during the outbreak.