US President Donald Trump has entered into an “unseemly” war of words with the widow of a US soldier killed in Niger this month.

Myeshia Johnson, widow of Sergeant La David T Johnson, said in a television interview that Mr Trump made her “cry even worse” during a condolence telephone call during which he allegedly said her husband “knew what he signed up for”.

Ms Johnson also confirmed earlier claims that the President did not remember her husband’s name.

“The only way he [Mr Trump] remembered my husband’s name is because he had my husband’s report in front of him and that’s when he actually said ‘La David’,” Md Johnson said,

“I heard him stumbling on trying to remember my husband’s name. And that’s what hurt me the most. If my husband is out here fighting for our country, and he risked his life for our country, why can’t you remember his name?”

President Trump has angrily rejected the claims he was disrespectful since they emerged last week.

In a Twitter post on soon after the TV interview aired, the President said: “I had a very respectful conversation with the widow of Sgt. La David Johnson, and spoke his name from beginning, without hesitation!”

I had a very respectful conversation with the widow of Sgt. La David Johnson, and spoke his name from beginning, without hesitation!

— Donald J. Trump (@realDonaldTrump) October 23, 2017

Sergeant Johnson was one of four US soldiers killed on October 4 during an attack in the West African nation.

Last week, a member of the US House of Representatives, Frederica Wilson, said she had listened to the call from Mr Trump and that he had upset the family by saying Johnson “knew what he signed up for.”

That drew a sharp rebuke from the President, who dubbed Wilson “whacky” and denied her account of the call.

“I didn’t say what that congresswoman said,” Mr Trump told reporters last week.

“I had a very nice conversation with the woman, with the wife who … sounded like a lovely woman.”

In Monday’s interview, Ms Johnson said, “The president said that he (her husband) knew what he signed up for, but it hurts anyway …And it made me cry because I was very angry at the tone of his voice and how he couldn’t remember my husband’s name.”

Ms Johnson said that when Mr Trump called, she and other family members were in a limousine riding to an airport where her husband’s body was shipped. Ms Wilson was also in the car.

Ms Johnson said she did not say anything during the call, adding that afterward, she was “very upset and hurt. It made me cry even worse”.

Asked what she might now say to Mr Trump, Johnson said she had “nothing to say to him.”

The widow also said that the military has told her little about what happened in Niger, and that she is upset that she has not been allowed to see her husband’s body.

“I don’t know what’s in that box,” said of her husband’s coffin. “It could be empty for all I know.”

The attack earlier this month, which US officials suspect was carried out by a local affiliate of Islamic State, has thrown a spotlight on the US counter-terrorism mission in Niger, which has about 800 US troops.

– With AAP