MANILA, Oct 23 (Reuters) Philippine police today said it was unlikely a bomb caused last week's explosion that killed 11 people and wounded more than 100 at an upscale shopping mall in Manila's financial district.
Geary Barias, Manila's police chief, said Friday's lunchtime blast could have been caused by an accumulation of deadly gas in the basement of the Glorietta shopping complex owned by the country's richest family, the Zobel de Ayalas.
''It was difficult to support a bomb blast theory because our investigators did not find any bomb fragment at the site,'' Barias told reporters, adding the probe was ongoing.
Experts, however, have said the blast, which blew a hole in the roof of the mall, could not have taken place without sabotage.
Ayala Land Inc which runs the complex, is conducting its own inquiry, a spokesman said. The damage to the mall was put at 100 million pesos (2.27 million dollars).
President Gloria Macapagal Arroyo toured the blast site on Tuesday and called for patience with the police inquiry.
''Let them be the ones to answer all those questions,'' she told reporters.
There were rumours the blast was the handiwork of Muslim rebels after traces of a high-grade explosive substance, RDX, was found near the site. But police have said a claim of responsibility by a small Muslim group was a hoax.
Some Filipinos have speculated the government itself was behind the attack to divert attention from a slew of bribery scandals. Officials dismissed the rumour as nonsense.
''It is a measure of the deep public distrust for the Arroyo administration that so many people instinctively speculated it to have engineered the explosion,'' said today's editorial in the Philippine Daily Inquirer.
Barias said investigators had not found any bomb crater.
''The crater is critical in any bomb blast investigation,'' he said, adding the upward direction of the blast supported the theory of a gas explosion.
He said experts also found defects in the construction of a 4,000-litre diesel tank at the basement.
But Ernesto dela Cruz, a chemical engineering professor at the University of the Philippines, told reporters a mix of diesel and methane gas would result in fire, not an explosion.
''You need to heat diesel up to 200 centigrade to vaporise the fuel and make it explode,'' dela Cruz said on local radio, adding methane by itself would not explode unless something set it off.
REUTERS ARB HT1417