For decades, the Canadian and American defence agency NORAD has provided updates on Santa Claus's international gift delivery route, but this year, for the first time, US astronauts lent a hand.

"We have obtained visual confirmation that Santa is currently travelling south over India," Andrew Morgan said via a video link as he floated at zero gravity in the International Space Station (ISS).

The North American Aerospace Defence Command (NORAD) said that the ISS was travelling at 27,000 kilometres an hour, 250 miles above Earth - providing "a great vantage point to spot Santa on his annual journey around the world."

"NORAD appreciates the support of Colonel Morgan and the ISS team," it added.

The agency reported that Santa and his reindeer were near Managua, Nicaragua at 0505 GMT Wednesday and had delivered more than 5.7 billion gifts after hours of giving. They took off from the North Pole at 0930 GMT Tuesday.

NORAD has been tracking Santa since 1955 when a girl dialled a misprinted phone number from a department store advertisement in the local newspaper, believing she was calling Santa.

The number rang into the Air Defence Command Operation Centre, where an officer was quick to realise the mistake and assured her he was Santa.

Each year since, NORAD has reported Santa's location to millions across the globe, with noradsanta.org this year live-tracking his present-filled red sleigh pulled by nine reindeer.

Today, 1,500 volunteers help the military answer calls and emails from children.

US first lady Melania Trump joined the effort, listening to several children from across the United States tick off items on their Christmas lists. She reminded them to put out milk and cookies for Santa.

The US Department of Agriculture said that "Mr S. Nicholas Claus" and his reindeer had been granted a special movement permit to enter the country and were "fit for landing on rooftops."