The rare sightings of sharks in Bermuda's most popular bay yesterday has caused little concern for experts over the safety of swimmers on the Island.

Principal curator of the Bermuda Aquarium, Museum and Zoo Jack Ward said last night that people should not be overly worried because shark attacks on humans were rare.

And he said contact between sharks and swimmers around the Island's waters were probably a lot more common than believed. It was just that people were totally unaware of it.

He said: "Sharks contact humans for more than humans know. They see us long before we know they are there. We are in their environment, but more often than not, the shark will avoid direct contact.

"I would envisage that humans would be a deterrent to sharks.

"People and sharks coming together is very rare, and the likelihood of there actually being an attack is extremely low.

"Sharks are relatively benign creatures . They are great guys and we should leave them alone."

Mr. Ward said the most abundant type of sharks around Bermuda's waters were the Galapagos and Dusky sharks, which were darkish grey in colour, and not known for their aggressive behaviour.

The difference between the two is minute, he said, and it was not uncommon for them to swim near to the Island's shoreline, especially at night, or follow cruise ships into Hamilton Harbour.

Sharks sometimes swim in packs, or alone, but numbers worldwide are decreasing due to the fishing habits of humans and the shark's slow and limited reproductive ability - only producing one or two pups at a time. However, yesterday's occurrence of them actually coming into a busy bay and swimming in only two feet of water was extremely rare. But he said no-one could begin to speculate what had brought the sharks so close.

He said: "There is nothing keeping them from coming in to the reef. At night, in the past, some very large sharks have been caught.

"It was unlikely that it was the splashing of the swimmers that brought them in because there is much more splashing action from the waves hitting the rocks. And there is plenty of food outside of the bay.

"People should not panic. It's distressing to swimmers, I know, and they have a threatening persona, but sharks have been out there in larger numbers in the past. There simply aren't as many of them around now."

Ralph Richardson, of the Bermuda Underwater Exploration Institute, said he believed there was no cause for panic, but said he was interested in what had brought them so close to the shore, especially as Florida was recording more sightings than usual. He said: "It's very rare for Bermuda. I don't know what could have brought them in. All of the conditions of today and last night have existed before - they were nothing new.

"It could have been something to do with mating, or could have just been a rogue pack of sharks that wandered into the bay. They may not have been hungry at all. I don't believe there were any big schools of fish in the bay at the time."

He said: "I am wondering whether there is some sort of global condition that could cause them to come to shore. I have no idea what, but it is all very interesting.

"I think we will have to wait and see if they come back."