The acting US navy secretary said he was sorry for calling the commander of a coronavirus-stricken aircraft carrier "too naive or too stupid", drawing a response from President Donald Trump who called the criticism "a rough statement".

"I apologise for any confusion this choice of words may have caused," Thomas Modly said late on Monday, adding he does not believe Captain Brett E Crozier is stupid or naive.

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"I also want to apologise directly to Captain Crozier, his family, and the entire crew of the carrier for any pain my remarks may have caused," he said referring to his speech that was widely reported in the media.

Modly's public ridicule came after a letter by the revered former commander pleading for help for his coronavirus-stricken aircraft carrier was leaked. Subsequently, Crozier was relieved of his duties.

"If he didn't think that information was going to get out into the public in this information age that we live in, then he was ... too naive or too stupid to be a commanding officer of a ship like this," Modly said earlier. "The alternative is that he did it on purpose."

Crozier, who took command of the Theodore Roosevelt in November, wrote a four-page letter describing a bleak situation on board the carrier as more of his crew began falling ill.

In his letter, Crozier called for "decisive action" - removing more than 4,000 sailors from the ship and isolating them - and said unless the navy acted immediately it would be failing to properly safeguard "our most trusted asset - our sailors".

According to a person familiar with the conversation, Defense Secretary Mark Esper's staff told Modly he must apologise. The official spoke on condition of anonymity to discuss a private conversation.

'Tone-deaf'

Crew members have been taken off the ship to be tested for the coronavirus. At least 173 sailors on board the ship tested positive as of Monday, and about 2,000 of the 4,865 crew members had been taken off. The navy has offered no estimate of when the ship might return to duty.

While skewering Crozier, Modly also admonished the crew. He suggested by cheering Crozier when he departed the carrier last week, they were overlooking their most basic duty to defend US interests.

"So think about that when you cheer the man off the ship who exposed you to that," he said. "I understand you love the guy. It's good that you love him. But you're not required to love him."

A sailor on board the ship told Reuters news agency that Modly's speech only angered the crew.

"Nobody likes what he had to say... He made everyone more irritated," said the sailor, who spoke on condition of anonymity.

Chairman of the House Armed Services Committee Adam Smith, a Democrat, called on Monday for Modly's removal.

"Acting Secretary Modly's decision to address the sailors on the Roosevelt and personally attack Captain Crozier shows a tone-deaf approach more focused on personal ego than one of the calm, steady leadership we so desperately need in this crisis," Smith said in a statement.

Crozier 'made a mistake'

President Trump on Monday said he may get involved, agreeing that Modly's criticism of Crozier was "a rough statement". He said Crozier made a mistake when he sent a memo to several people laying out his concerns about the crew and the virus.

"You have two good people and they're arguing... I'm good at settling these arguments. So I may look into it in great detail ... and I'll be able to figure it out very fast," Trump said.

The president said Crozier had a good career prior to this incident, adding, "I don't want to destroy somebody for having a bad day."

In his apology, Modly said he believes Crozier is "smart and passionate".

"I believe ... he sent his alarming email with the intention of getting it into the public domain in an effort to draw public attention to the situation on his ship," he said.