More than 120,000 people have signed a petition calling on the U.S. Navy to reinstate the captain of a coronavirus-stricken aircraft carrier a day after he was relieved of his command for a letter sent to superiors urging stronger measures to halt the outbreak.

Captain Brett Crozier was relieved of his command of the USS Theodore Roosevelt on Thursday after a scathing letter in which he called on the Navy to take "decisive action" to halt the spread of the virus aboard the nuclear-powered aircraft carrier was leaked to the media. 

"His actions possibly saved many lives," the online petition said. "Although he was fired, his plan to safely remove crew members was still implemented. He is a hero who should be rewarded."

On Friday, one day after the launch of the petition on Change.org, over 123,000 people had signed, well on the way to the goal of 150,000.

Crozier called for removing more than 4,000 sailors from the ship and isolating them, and wrote that unless the Navy acted immediately it would be failing to properly safeguard "our most trusted asset - our sailors."

However, U.S. Defense Secretary Mark Esper backed the Navy's firing, the Pentagon said on Friday.

"The secretary of defense supported the secretary of the Navy's decision to remove him," Pentagon spokesman Jonathan Hoffman told a news briefing, saying Esper's decision was based on acting Navy Secretary Thomas Modly's conclusion that he had lost confidence in Crozier. 

Asked if Esper still had confidence in Modly, Hoffman said: "He does."

Meanwhile, a group of prominent Democratic senators formally requested on Friday that the Pentagon's independent Inspector General investigate the Navy's firing of the commander.

"Given the extraordinary circumstances under which these events took place, we believe a closer examination by a neutral third party is warranted," the senators wrote, according to Reuters.

Senator Richard Blumenthal of Connecticut and Senator Chris Van Hollen of Maryland led the push and were joined by 15 other U.S. senators, including Bernie Sanders, Elizabeth Warren, Amy Klobuchar and Kamala Harris.

(With input from Reuters)