Donald Trump reportedly tore out a magazine picture of Justin Trudeau, scrawled a brief note about the Canadian prime minister “looking good”, and made White House officials mail it to the neighbouring country’s embassy.

The message – first reported by Axios – is said to have been written by the US president on the torn-out cover of a May 2017 issue of Bloomberg Businessweek, which featured an image of Mr Trudeau alongside a caption reading “The Anti-Trump”.

On it, Mr Trump reportedly jotted a note reading something to the effect of, “Looking good! Hope it's not true!" according to the US news outlet.

The Canadian ambassador considered the note so strange he thought it was a prank, but after calling US officials was told the note was genuine.

Although some White House staff reportedly considered the note inappropriate, the National Security Council ultimately decided it was done in good humour and would be considered by Ottawa to be friendly contact.

Another exchange in December of that year reportedly saw Mr Trump send Mr Trudeau a document purporting to show a US trade deficit with Canada.

Mr Trudeau reportedly responded by including in his letter a printout of a US government website showing America actually has a trade surplus over its neighbour when services are included with goods.

A May 2017 Bloomberg Businessweek front page featuring Canadian prime minister Justin Trudeau (Bloomberg)

The Canadian prime minister reportedly included a smiley face alongside the document.

The White House has been contacted for comment.