A competitive cyclist from Britain has been killed after a car struck him on the Monaro Highway as he was riding towards Canberra, in the 5,500-kilometre Indian Pacific Wheel Race.

It is understood well-known endurance cyclist Mike Hall was travelling north, just inside the ACT border, when the accident happened about 6:30am — before daylight — today.

Indian Pacific Wheel Race route covers about 5500km, 2017. ( Supplied: Indian Pacific Wheel Race )

Hall was pronounced dead at the scene, and the driver of the car was taken to hospital.

The race, which sees riders trek from Fremantle to Sydney, commenced on March 18, with about 70 cyclists setting off across the Nullarbor.

An initial statement from the race organisers said they would cooperate fully with investigations.

They subsequently announced the event had been cancelled.

"Our deepest sympathies go to Mike's family and to all those who knew him. Mike will be sorely missed … this tragedy is a great loss to the global cycling community," the organisers said in a statement.

Hall was sitting in second place, having covered about 5,000km already, when the collision occurred.

The cyclist was pronounced dead at the scene. ( ABC News: Francis Keany )

He was well known in cycling circles, having won both the longest mountain bike race in the world, the Tour Divide, and also the longest road bicycle race, the World Cycle Race.

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Just a day prior to the accident, Hall appeared in a video on a cycling YouTube channel, speaking about the gruelling event.

"I keep thinking that I can't stay awake … I'm just really tired," he said.

On social media, fans and fellow riders were swift to post tributes to the accomplished rider.

A fellow competitor posted these words on Facebook, after learning of his death:

"I'm sitting by the side of the road in tears. Ride in Peace."

Police said Hall's family had requested that the media respect their privacy.

A tribute ride in his honour was being planned, to be held in Sydney on Sunday.

Police investigating crash

Hall's death is the third fatality on ACT roads this year.

Sergeant Chris Meagher said the driver was assessed by police at the scene before being taken to hospital.

"That driver is in shock and will be spoken to later," he said.

"There is no suggestion of speed or alcohol at this stage."