President-elect Joe Biden has been speaking personally with world leaders as Donald Trump let loose with a barrage of tweets claiming “BALLOT COUNTING ABUSE”.

Mr Trump has ramped up legal action in key states like Pennsylvania and increased his presence on Twitter, letting fly with a series of claims in capital letters.

He is expected to make his first public appearance since Saturday (US time) with a visit to Arlington National Cemetery on Wednesday.

Meanwhile Mr Biden has spoken to key American allies, British Prime Minister Boris Johnson, French President Emmanuel Macron and German Chancellor Angela Merkel.

Speaking later to media and taking his first questions since the ballot was declared, Mr Biden was asked about the transition to the presidency which he said was on track.

When asked about Mr Trump’s refusal to concede, Mr Biden said: “I think it’s an embarrassment, quite frankly,” before pausing and adding: “It will not help the President’s legacy”.

Britain’s conservative prime minister was among the first European leaders to congratulate Mr Biden in a phone call that lasted 25 minutes.

Mr Johnson, who had a warm relationship with Mr Trump, said he looked forward to working with the incoming Democrat.

“I just spoke to @JoeBiden to congratulate him on his election,” he tweeted.

“I look forward to strengthening the partnership between our countries and to working with him on our shared priorities – from tackling climate change, to promoting democracy and building back better from the pandemic.”

I just spoke to @JoeBiden to congratulate him on his election. I look forward to strengthening the partnership between our countries and to working with him on our shared priorities – from tackling climate change, to promoting democracy and building back better from the pandemic.

— Boris Johnson (@BorisJohnson) November 10, 2020

Mr Johnson’s office said the two men “discussed the close and longstanding relationship” between the two countries and promised to strengthen those bonds in areas including trade and security.

They also promised to work on “shared priorities, from tackling climate change, to promoting democracy and building back better from the coronavirus pandemic,” Downing Street said.

Mr Johnson invited Mr Biden to attend the COP26 climate change summit in Glasgow next November and said he looked forward to seeing him at a G7 summit that the UK is due to host in 2021.

The French president’s office released a video of Mr Macron in his office, offering congratulations to Mr Biden and vice president-elect Kamala Harris during a call on Tuesday afternoon.

I spoke to @JoeBiden to congratulate him on his election. We’ll have a lot to do together to promote shared priorities – climate, global health, international security – and effective multilateral action. pic.twitter.com/h1zStqEf2J

— Emmanuel Macron (@EmmanuelMacron) November 10, 2020

It comes as Mr Trump let loose with a flurry of tweets reiterating claims of election fraud and insisting he was on track to win the US election.

Twitter placed disclaimers on Mr Trump’s latest tweets warning his 89 million followers: “This claim about election fraud is disputed”.

Mr Trump wrote: “WATCH FOR MASSIVE BALLOT COUNTING ABUSE AND, JUST LIKE THE EARLY VACCINE, REMEMBER I TOLD YOU SO!.

“WE ARE MAKING BIG PROGRESS. RESULTS START TO COME IN NEXT WEEK. MAKE AMERICA GREAT AGAIN!

“WE WILL WIN!

“BALLOT COUNTING ABUSE!,” he tweeted.

Earlier, sharp-eyed social media users spotted the word “Trump” showing faintly in the background of a message in Boris Johnson’s tweet congratulating Joe Biden.

A “technical error” led to parts of the message being left visible in an official tweet, a UK government spokesman said.

He said the government had prepared two different statements because the contest was so close but that a technical error meant parts of the alternative message were embedded in the background of the graphic congratulating Biden.

The Guido Fawkes website published a picture of the tweet after it had adjusted the contrast and brightness levels of the image.

It appeared to show Mr Trump’s name, the words “second term” and “on the future of this” in the background of the tweet congratulating Mr Biden.

“As you’d expect, two statements were prepared in advance for the outcome of this closely contested election. A technical error meant that parts of the alternative message were embedded in the background of the graphic,” a government spokesman said.

-with AAP