US President Donald Trump has offered to send experimental Covid-19 treatment to help Prime Minister Boris Johnson as he's in intensive care.

The President has championed a combination of the anti-malaria drug hydroxychloroquine and an antibiotic azithromycin as a 'game-changer' in the fight against coronavirus. 

However, his medical advisers have said there is no proof they are effective. 

Speaking at a White House press conference in which he said all Americans were praying for Mr Johnson, the President said he wanted to help in anyway he could.

“I’ve asked two of the leading companies ... they’ve come with the solutions and just have done incredible jobs – and I’ve asked him to contact London immediately.

“They’ve really advanced therapeutics … and they have arrived in London already. The London office has whatever they need. We’ll see if we can be of help. We’ve contacted all of Boris’s doctors, and we’ll see what is going to take place, but they are ready to go.

“They’ve had meetings with the doctors, and we’ll see whether or not they want to go that route. But when you’re in intensive care it’s a big deal. So they’re there and they’re ready.”