Marine conservationists have urged beach-goers to show basking sharks respect after the latest pictures reveal a swarm of surfers within touching distance of the timid creatures.

Experts fear sharks could be injured or frightened by surfers, swimmers and other water users trying to get as close as possible to the gigantic fish.

The fresh appeal comes after these pictures show a handful of surfers within a few metres of a basking shark which was feeding on plankton off Porthcurno beach, near Land's End, Cornwall.

Richard Peirce, chairman of the Devon-based Shark Trust, urged sea-users to exercise "caution and respect" when in the water with basking sharks.

He said: "Very often, simply stopping in their line of travel is a good way to get a close look at the sharks. They will see you and, if they want, come a bit closer. But it is their choice.

"There is a risk that chasing basking sharks will harass them. Although these sharks are not flesh-eaters, they weigh about the same as a single-decker bus, and should not be messed with."

Basking sharks are a common sight off Devon and Cornwall's coastal waters each summer, with their presence often marked by their large dorsal fin.

But experts have asked shark fans to keep their distance. The Shark Trust has now published a Code of Conduct, advising the best way to behave around sharks.

For more information, visit www.sharktrust.org.