US President Donald Trump and First Lady Melania Trump made an unexpected — and brief — visit to pay their respects to late president George H.W. Bush in Washington.

The Trumps made an unannounced visit to the US Capitol’s rotunda, where Mr Bush is lying in state as part of multiple days of services and tributes to honour the 41st US president.

The couple entered the rotunda and held hands as they approached Mr Bush’s coffin draped in the American flag.

Mr Trump saluted Mr Bush’s remains while the first lady pressed her right hand over her heart.

First the couple stood for a few moments before the coffin with their eyes closed, according to the Associated Press. As soon as Mr Trump saluted, they left.

Observers noted that the first couple stayed for barely a minute.

They exited the rotunda with little fanfare.

Mr Bush never warmed to Mr Trump, and he had let it be known that he did not vote for him in 2016. Mr Trump himself has criticised the elder Bush on the campaign trail.

But on Monday, Mr Trump wrote to members of Congress, telling them to hail Mr Bush as a man who “led a life that exemplified what is truly great about America.”

“President Bush worked selflessly throughout his long life to bring about a world of justice and lasting peace,” he wrote.

Mr Bush was a decorated World War II fighter pilot, one-time ambassador to China, former head of the Central Intelligence Agency, and vice president to Ronald Reagan before winning the White House.

Military pallbearers carried the flag-draped casket into the rotunda as a fiery sunset bathed Washington in a glow.

The sombre ceremony was attended by his son George W. Bush — the nation’s 43rd president — and other relatives, dignitaries and more than 100 members of the House and Senate.

Senate Majority Leader Mitch McConnell lauded Mr Bush — who occupied the White House from 1989 to 1993 — as a patriot who steered the country as straight as he had piloted his World War II aeroplane.

“He kept us flying high and challenged us to fly higher still. And he did it with modesty and kindness that would have been surprising in someone one tenth as tough and accomplished as he was,” he said.

The commemorations will continue this week, with the state funeral service at the Washington National Cathedral scheduled for Wednesday — the first presidential funeral since Gerald Ford died in 2006.

Mr Bush’s body will then be flown back to his home state of Texas where he will be buried alongside his wife Barbara and infant daughter in the grounds of Texas A&M University, where his presidential library is housed.

Mr Trump has declared Wednesday a national day of mourning, and plans to attend the funeral.

“Looking forward to being with the Bush Family to pay my respects to President George H.W. Bush,” Mr Trump tweeted on Monday.

Mr Bush died Friday at age 94, at his home in Houston — “a very gentle and peaceful passing,” in the words of his lifelong friend and adviser James Baker.