King Charles has highlighted the UK’s “relationship founded on friendship” with the US as the country celebrates 250 years since the Declaration of Independence.

The document, signed in 1776, established the United States of America’s independence from the colonial rule of Great Britain – its anniversary is celebrated on 4 July.

In a message to President Donald Trump and the American citizens, external, the King said that “through centuries of shared challenge and achievement” the two countries have built “trust and a belief in liberty, the rule of law and the dignity of all people”.

He added that “as we look ahead to the next 250 years, I have no doubt we will continue to defend our shared values”.

“The connection between our people is one that I trust will only grow stronger with time.”

It comes as Trump is set to attend celebrations in Washington DC today, including flyovers by hundreds of aircraft and a fireworks display.

The Fourth of July fireworks display is an annual tradition in Washington DC and Trump has promised that this year’s version – which is scheduled to begin after his remarks – would be the “largest fireworks show in history”.

Festivities are also taking place in other parts of the US.

The Times Square Ball in New York will drop eight times to signal midnight in every US time zone.

In Philadelphia, where the Declaration of Independence was signed in Independence Hall 250 years ago, there will be a celebration concert featuring stars including Christina Aguilera and Meek Mill.

In May, the King and Queen Camilla visited the US for the first British state visit to the country since Queen Elizabeth II’s visit in 2007.

The Royals travelled against a backdrop of political tension after the UK government decided to not get involved in the Iran war.

In a speech to US Congress, the King urged US lawmakers to defend Ukraine and support Nato.

A senior royal aide said of the pair’s relationship during the trip: “They get on very well… It’s a pairing, sort of unlikely though it might be in many ways…”

“I mean, given some of the issues that have presented themselves in the bilateral relationship, you’d think it might all be a bit tricky.”

And Trump’s review seemed clear: “The greatest king in my book.”