WASHINGTON (Reuters) - The first U.S. military service member has died from the coronavirus, the Pentagon said on Monday, as it reported another spike in the number of infected troops.

The service member was a New Jersey Army National Guardsman who tested positive for COVID-19 - the disease caused by the coronavirus - and had been in hospital since March 21. He died on Saturday, the Pentagon said.

“Today is a sad day for the Department of Defense as we have lost our first American service member - active, reserve or Guard - to coronavirus,” Defense Secretary Mark Esper said in a statement. “This is a stinging loss for our military community, and our condolences go out to his family, friends, civilian co-workers and the entire National Guard community.”

The nationwide death toll from the coronavirus pandemic climbed past 3,000 on Monday, the deadliest day yet.

The New Jersey National Guard identified him as Captain Douglas Linn Hickok, a drilling guardsman in Medical Command and a civilian physician assistant, originally from Jackson, New Jersey.

“Our thoughts are with his wife, children, and their family,” New Jersey Governor Phil Murphy wrote on Twitter.

General Joseph Lengyel, chief of the National Guard Bureau, lamented the death and said “all of us are likely to know people directly affected by this virus in the coming weeks.”

Earlier on Monday, the Pentagon said that 568 troops had tested positive for the coronavirus, up from 280 on Thursday. More than 450 Defense Department civilians, contractors and dependents have also tested positive, it said.

Reuters reported last week that the U.S. military has decided to stop providing more granular data about coronavirus infections within its ranks, citing concern that the information might be used by adversaries as the virus spreads.

The new policy, which the Pentagon detailed in a statement on Monday, appears to underscore U.S. military concerns about the potential trajectory of the virus over the coming months - both at home and abroad.

There has been a sharp increase in coronavirus cases among troops inside the United States, which officials tell Reuters have overtaken the number of cases among forces overseas in key branches of military.