The US President’s announcement came shortly after news that Boris Johnson had been admitted to intensive care last night. Trump issued his apologies and wished the UK Prime Minister well, adding that the US was praying for him to get through the virus the other side.
He confirmed that his administration had contacted “all of Johnson's doctors".
He added that he had asked two leading companies that helped find treatments for AIDS and Ebola to contact London immediately.
It came during the president’s daily coronavirus news conference at the White House.
Paying tribute to Mr Johnson, Trump said: "I want to send best wishes to a very good friend of mine, and a friend to our nation, Prime Minister Boris Johnson.
Trump has asked two leading companies to assist Boris Johnson in his fight against coronavirus
The tributes come as Trump struggles to grapple with the virus' spread in the US
"We are very saddened to hear that he was taken into intensive care this afternoon.
"Americans are all praying for his recovery - he's been a really good friend and something very special: strong, resolute, doesn't quit, doesn't give up.”
Discussing the coronavirus, he later admitted: "When you get into intensive care it really, really gets serious with this disease."
On Monday Mr Johnson was admitted to intensive care after his coronavirus symptoms declined.
JUST IN: Carrie Symonds fears: Prayers pour in for pregnant fiancée of Boris
Trump stands with Dr Anthony Fauci
He had already entered hospital on Sunday on the advice of his doctor.
Number 10 said Mr Johnson remains conscious and was moved to intensive care as a precaution should he require ventilation in the coming days.
Mr Johnson is said to be receiving “excellent care” in an NHS hospital in London.
Foreign Secretary Dominic Raab has taken on the role of First Secretary of State and Secretary of State and has been asked by Mr Johnson to deputise "where necessary”.
Queen issues statement as Boris Johnson moved into intensive care [LATEST]
Britons demand Clap for Boris as voters rally support for PM [ANALYSIS]
Dominic Raab is currently spearheading Downing Street while Boris Johnson battles the virus
The foreign secretary will now chair Cobra meetings
The Queen has been kept informed about the prime minister’s health by Downing Street, according to Buckingham Palace.
Mr Johnson was given oxygen late on Monday afternoon before being taken into intensive care, according to the BBC’s Chris Mason.
A Number 10 statement read: "The prime minister has been under the care of doctors at St Thomas' Hospital, in London, after being admitted with persistent symptoms of coronavirus.
"Over the course of (Monday) afternoon, the condition of the prime minister has worsened and, on the advice of his medical team, he has been moved to the intensive care unit at the hospital."
A live coronavirus map of the UK
It was confirmed on March 27 that Mr Johnson had contracted COVID-19, a disease caused by coronavirus.
Yet reports suggested that he continued to work 16 hour days in order to get on top of the fight against coronavirus.
The virus isn’t the only challenge Mr Johnson has faced, with Russian media apparently the newest threat.
Publication RIA-Novosti reported the unverified news that the prime minister would soon be placed on a ventilator, attributing its source to someone “close to the leadership” of the NHS.
Johnson was reportedly working 16 hour days despite having the virus
Mr Johnson’s spokesperson was quick to dismiss the news as “disinformation”.
They said: “Our specialist government units have seen a rise in false and misleading narratives since the coronavirus pandemic started.
"It's vital that any disinformation is knocked down quickly."
He also revealed that the government was working with social media companies to "press for further action to stem the further spread of falsehood and rumours".