The cause of the inferno which destroyed Brighton's historic West Pier may never be known.

Fire brigade officials have refused to risk lives by putting a team of investigators on to the remains of the 137-year old pier.

They believe it is too dangerous for anyone to set foot on the structure and they doubt they will ever know how Friday's blaze started.

After studying footage from seafront CCTV cameras, police have ruled out any involvement by the occupants of a speedboat seen near the pier shortly before the alarm was raised.

Arson remains the suspected cause of the blaze and police have renewed appeals for information on anyone seen acting suspiciously near the pier.

Meanwhile, the still smouldering pier has become a tourist attraction in its own right, luring thousands of onlookers from all over the south-east.

Seafront traders, although saddened by what has happened, have noted an upsurge in custom.

Frank Davis, East Sussex Fire Brigade's investigations officer, said: "We are not going to risk putting ateam on to the pier. It is far too dangerous.

"While it is very sad we have lost a Grade I listed building, it is not something we would consider worth risking a single human life for.

"There is no way of getting on to it from the land end until the bridge destroyed in the winter storms is rebuilt.

"If we could get a lifeboat alongside, there is still danger from falling debris and then how would we get a team off the boat and on to the pier?

"Even if we could overcome those problems it is still unlikely we would be able to find out how it started.

"Any evidence is almost certain to have been destroy-ed by the intensity of the fire.

"The rest is likely to have fallen into the sea and been washed away by the tide by now.

"We would need a structural engineer to have a look at what remains of the pier first to find out if it is safe to walk on.

"That is something the West Pier Trust is going to have to have done anyway, but I have no idea how long that will take.

"If they still want us to try to establish a cause after that, it is something we will consider. However, there will be very little evidence by then."

Rachel Clarke, manager of the West Pier Trust, said the decision was sad but understandable in the circumstances.

She said meetings were planned next week between the Trust, Brighton and Hove City Council and developers St Modwen to decide what should happen next.

She said: "The structure had been unsafe for anyone to go on to for some time and we have not been on it for about 18 months.

"It is sad we will probably never know what caused the fire but we would not want to put anyone's life in danger.

"The metal skeleton of the original structure is still there and we will have to find out how badly the fire has damaged it.

"It would be nice to keep some of the metalwork but I suspect it may well have to be demolished.

"Whatever happens, the restoration will be an authentic reconstruction of the original and people do not need to be concerned it will be replaced by something more modern."

City council leader Ken Bodfish met representatives from the Trust and St Modwen on Friday and said the £30 million restoration project was still on course despite the fire.

He said it did not come as a surprise that the cause was not likely to be discovered. He said: "I would not want to see the lives of the investigators put in danger to discover the cause.

"Even if we did establish the cause as arson it is very unlikely we will ever find out who was responsible, so I can see little point."