DONALD Trump has claimed a congress-woman “fabricated” an account of him telling the widow of a US soldier killed in an ambush in Niger that her husband “knew what he signed up for”.

Frederica Wilson said she was in the car with Myeshia Johnson on Tuesday on the way to Miami International Airport to meet the body of Johnson’s husband, Sergeant La David Johnson, when the president called.

Wilson said she and others heard part of the conversation on speakerphone.

Asked by Miami station WPLG if she heard Trump say that she answered: “Yeah, he said that. To me, that is something that you can say in a conversation, but you shouldn’t say that to a grieving widow. That’s so insensitive.”

In tweet yesterday, Trump wrote: “Democrat Congresswoman totally fabricated what I said to the wife of a soldier who died in action (and I have proof). Sad!”

The president did not specify what proof he had.

Wilson stood by her account, saying: “The president evidently is lying, because what I said is true,” adding that others in the car with Johnson heard Trump.

Escalating her criticism, Wilson said: “He doesn’t even know how to sympathise with people. We’re grieving. This is a grieving community.

“It’s disgraceful for him to even tweet about this. This gentleman has a brain disorder and he needs to be checked out.”

Sgt Johnson was among four servicemen killed in the African nation of Niger earlier this month when militants thought to be affiliated with Daesh ambushed them while they were patrolling with Nigerian troops in unarmoured trucks.

Wilson said she did not hear the entire conversation, and Johnson told her she could not remember everything that was said when asked it about it later.

“When she hung up the phone she looked at me and said, ‘He didn’t even know his name’. Now that’s the worst part,” Wilson said.

Trump has been criticised for not reaching out straight away to relatives of the four killed in Niger.

On Monday, he said he had written letters that had not yet been mailed. His aides said they had been awaiting information before proceeding.

The incident came after Trump provoked a row by suggesting his predecessors as president failed to meet families of military personnel killed in war.

“Most of them didn’t make calls,” he said of his predecessors.

He said it was possible that Barack Obama “did sometimes” but “other presidents did not call”.

Meanwhile, Trump has been on the receiving end of insults from Iran’s supreme leader, who has described him as “mentally retarded”.

Ayatollah Ali Khamenei’s was urging Europe to do more to back the 2015 nuclear deal after the president refused to re-certify the pact.

European companies have rushed into the Iranian markets since the landmark accord, and Khamenei’s comments show he hopes to leverage them into protecting the nuclear deal.

While offering harsh criticism of Trump, Khamenei wants to ensure that Tehran continues to have access to the international market for its crude oil as part of efforts to revive a stagnant economy.

“The European governments have underlined the nuclear deal’s issue and condemned the US president’s remarks,” Khamenei said, according to comments posted on his official website.

“We welcome this approach but it is not enough that they only tell him not to tear up the deal. The nuclear deal is to their benefit.”

He said: “I will not spend time to respond to the nonsensical comments by the foul-mouthed president,” and referred to Mr Trump and his administration as “mentally retarded”.

He also warned that if the US tears up the deal, “we will shred it into pieces”.

The 2015 deal curbed Tehran’s nuclear programme in exchange for lifting international sanctions on Iran.

Britain, China, France, Germany, Russia and the European Union – the other parties to the nuclear accord – have been telling Trump’s administration to stay in the deal.

His refusal last week to re-certify has sparked a new war of words between the Islamic Republic and America, fuelling growing mistrust and a sense of nationalism among Iranians.

Trump also criticised Europeans for their participation in Iran’s energy projects.

He said he de-certified the accord on the grounds that Iran had committed several violations of the deal but he did not announce a withdrawal from the pact, instead shifting it to Congress for a decision.