HEMEL HEMPSTEAD, England (AP)--Firefighters got permission Monday to begin using foam to attack a huge blaze at an oil depot north of London, following concerns that attempts to extinguish the fire could contaminate the water supply.

Hertfordshire police said the fire service, the Environment Agency and police were all satisfied that foam could be used without danger of polluting water supplies. There had been fears that runoff from the site could contaminate surface and ground water with fuel.

"We will have a sustained attack for at least four hours and we are hoping that will have the effect we desire but we, along with you, will be waiting to see," said Roy Wilsher, chief fire officer in Hertfordshire county.

"We will know by midday today whether our plan of attack is going to be effective or not," Wilsher told British Broadcasting Corp. radio.

Explosions ripped through the Buncefield fuel depot 25 miles north of London Sunday morning, injuring dozens of people, blowing doors off nearby homes and sending balls of fire and clouds of black smoke into the sky.

Police said the blasts Sunday appeared to be accidental.

A huge plume of smoke continued to billow from the depot, the fifth-largest fuel distribution depot in the U.K. The terminal, operated by Total U.K., a unit of Total SA, and part-owned by Chevron Corp.'s (CVX) Texaco, stores 16 million liters of gasoline, diesel, kerosene and aviation fuel.

Police officers wearing breathing masks maintained a wide cordon around the site.

The national Environment Agency said it was concerned that substances including kerosene, diesel, gas oil and gasoline could escape from the site and pollute surface rivers and groundwaters.

The series of explosions Sunday came four days after an al-Qaida videotape appeared on the Internet calling for attacks on facilities carrying oil that it claims has been stolen from Muslims in the Middle East.

The powerful explosions, felt throughout a large swath of southeast England, also rattled nerves in a country still jittery over a July terrorist attack on London's subway and bus system that killed 52 people and the four suicide bombers.

"Around 6 a.m., as we were sleeping, there was a mighty explosion - a thunderclap that woke me up," said Neil Spencer who lives about three-quarters of a mile from the Buncefield terminal. "It was fireball after fireball - truly amazing."

Photographer Haris Luther who awoke to find the blast had destroyed the front door of his home, said: "I thought the house had been hit by lightning. It sounded like an earthquake."

Most of the 43 people injured were treated for cuts and bruises from the flying glass of broken windows in Hertfordshire. Two men with more serious injuries remained in local hospitals Sunday night, Hertfordshire Police said.

Noxious fumes from the fire, which left some people coughing, also affected the large squads of police who sealed off the area and evacuated nearly 300 people to a bowling alley being used as a temporary shelter. About 25 policemen were examined by doctors for problems such as chest tightness or shortness of breath, said Howard Bortkett-Jones, medical director of the two local hospitals.

The U.K.'s deadliest oil-related disaster was the July 6, 1988, explosion and fire on the North Sea oil platform Piper Alpha, off the Scottish coast, which killed 167 workers.

In 1994, a blast and fire at an oil refinery in Milford Haven, Wales, injured 26 workers and caused tens of millions of pounds in damage. Oil companies Texaco and Gulf were eventually fined for violating health and safety regulations.


(END) Dow Jones Newswires