'Bloody hell': Five-metre shark circles Australian kayaker

An Australian kayaker has told of his close encounter with a large shark off the country's west coast after capturing the moment on camera.

Ian Watkins estimated the shark was about four to five metres long. After it barged into his kayak, Watkins made an emergency call to nearby ships.

"This wave was coming behind me and I thought 'what the heck's that', and then I looked on and there's this massive fin, and I thought 'that's a serious shark'," he told ABC News.

"It pushed me from the left hand side and then it nudged me from the middle across the left hand side.

"I was trying to stay upright and then it circled me for a while and I got on the radio and said 'emergency, emergency, emergency'."

Mr Watkins said the shark was as big as his kayak, which is five metres long.

"I was more interested in staying upright," he said.

"Then he kept circling me, it went from the right under the kayak, then from the left under the kayak ...when it was coming under it was just really white it was massive and I thought 'holy ... bloody hell'."

His emergency call was picked up by Paul Guest, who was in his charter vessel about 600 metres away.

"We've got a bit of a panicked call from somebody who said they were on a ski or sea kayak and said they had a white pointer swimming around them and they needed assistance, because it was bumping into them and giving them a bit of grief," Mr Guest said.

"Passengers at the back of the boat pointed to him so we turned around and headed to them at full speed."

Having come to his aid, Mr Guest had some advice for him. "I told the guy maybe you should get a bigger boat."

It was the second shark scare in two days in Australia after a four-metre shark sent surfers off the west coast paddling frantically to shore.