Depth of Brazil subsalt oil raises leak risks:prof

* Oil safety equipment more likely to fail in deeper water

* Brazilian laws inadequate to deal with oil spills

By Denise Luna

RIO DE JANEIRO, May 25 (Reuters) - The future extraction of giant oil reserves off Brazil's coast faces greater risk of accidents than operations in the Gulf of Mexico because they are in much deeper water, a Brazilian engineering professor said on Tuesday.

The country found huge reserves in 2007 believed to hold some 50 billion barrels that lie under a layer of salt rock at various depths of up to about 7 kilometers (4.4 miles), considerably deeper than the waters where the recent BP accident took place.

"Depth is associated with the failure rate of the BOP (blow-out preventer), which showed itself to be inadequate at preventing a leak in the case of BP," said Segen Estefen, a naval engineering professor with the COPPE, an institute linked to the Federal University of Rio de Janeiro.

"The entire industry thought (the blow-out preventer) was adequate, but it wasn't enough," he said. "We need more effective equipment than the current BOP," Estefen said.

Another participant, Professor Alessandra Magrini, said Brazil had not made sufficient legal provisions to deal with an eventual oil disaster and was a signatory to few international treaties related to petroleum.

"The subsalt oil is coming and is at a distance from the coast that will take longer to reach, is more widely dispersed and could reach international waters," she said.

She said Brazil had "extremely weak" laws governing pollution from the oil industry which stipulated fines ranging from 7,000 Brazilian reais to 50 million ($3,747-$26.8 million).

British oil firm BP (BP.L) estimates about 5,000 barrels (210,000 gallons/795,000 liters) has been leaking into the ocean since an explosion on April 20 on the Deepwater Horizon rig in the Gulf of Mexico that killed 11 and threatens an environmental catastrophe.

The rig had been drilling to a depth of 13,000 feet below the sea bed, or nearly 4 km, while much of Brazil's subsalt lies much deeper. (Writing by Peter Murphy; Editing by Gary Hill)