Two airlines said flights due to take off or land in Taipei at about the time Flight SQ006 tried to leave for Los Angeles had been cancelled because of dangerous conditions brought on by Typhoon Xangsane.

Seventy-nine of the 179 people on board were killed when the Boeing 747-400 burst into flames and broke into three pieces as it tried to take off. Two injured passengers died in hospital Nov 2, pushing the death toll to 81. Another 82 people were injured and 16 were unhurt. Investigators are studying whether the plane hit an object or used the wrong runway.

In Singapore and Taipei, family members hit out at airline executives for leaving them in the dark for hours about the fate of their loved ones.

Relative Tan Yin Leong forced his way into a nationally televised news conference in Singapore to demand executives explain why he had had to learn of the death of his brother Yin Tong from the television news. Distraught and plagued by lack of sleep, Mr Tan wrestled past security personnel to shout: "We want to know what really happened. All our news is from the newspaper reporter and you are the ones who tell me . . . not to believe the press. Now, my brother is dead. Is dead!"

The airline apologised for having released the passenger list to the media before telling relatives, adding: "That was a most regrettable situation and we will not make the same mistake again."

It was a second public relations disaster for the airline. When news first broke of the crash, an airline spokesman in Los Angeles denied anyone had died, even though television pictures showed the charred wreckage on the runway.

About 24 family members who flew to Taipei from Singapore said they were dissatisfied with what they called the airline's deceptive tactics. In a reception set up for the family members, Cheong Choong Kong, airline deputy chairman, was heckled and interrupted while attempting to address the relatives.

"Nobody knows anything. We were just at the [Singapore] airport, crying, crying, crying!" one woman yelled. Mr Cheong, visibly shaken by the outburst, said: "The need for information and the need for accuracy and also the need to be considerate to the feelings of the people concerned . . . we were in a difficult position."

It was the airline's first fatal accident in its 28-year history. It stuck to its preliminary version of events that the most likely cause of the disaster was an object on the runway.

However, a spokesman conceded conditions were "not ideal", with Typhoon Xangsane whipping up strong winds and heavy rain. He said: "The pilot made the decision to take off because he felt the conditions were acceptable. The conditions were not ideal flying conditions obviously, but they were certainly well within safety limits."

Cathay Pacific said that four of its planes due to take off or land in Taipei in the hour before the crash aborted their plans because conditions were too dangerous. A spokeswoman said the decision had been taken by the pilots.

Taiwanese carrier EVA Air said it had cancelled three flights at about the same time because crosswinds exceeded its safety threshold of 88km/h. An EVA spokesman said the disclosure was not intended as a criticism of Singapore Airlines. The cancelled flights involved aircraft with large cargo doors, making them more vulnerable to winds than regular passenger jets.

Investigators said they were looking into whether the Singapore Airlines captain had tried to take off from the wrong runway. Most of the wreckage was on the 05-Right runway, which runs parallel next to the 05-Left runway, the runway the aircraft was supposed to leave from.

Jung Kai, director of Taiwan's cabinet-level Flight Safety Committee placed in charge of investigating the crash, said there were other factors besides the weather and the pilot's judgment that could have caused the aircraft to take off from the wrong runway.

"Based on the evidence gathered so far, at present the investigation is focusing on the factors of flight control, weather, equipment on the airport grounds and survival," Mr Jung said. He said lighting systems on the two runways were controlled by the same switch, meaning both sets of lights were on at the time of the accident.

Another report in the same edition of the SCMP said Cathay put about 800 passengers affected by the cancellations in hotel rooms overnight. They continued their journey on Nov 1 when the storm over Taipei had cleared and the airport had reopened. The last Cathay flight to land in Taipei before the crash was CX468, which touched down at about 9.10pm. The last to take off was flight 531, a passenger flight, just before 9pm.

A spokesman for Cathay pilots, Aircrew Officers' Association general secretary John Findlay, said Cathay Pacific pilots were "very experienced in flying around the region and, consequently, have considerable experience of the weather in the region.

"The [aborted] flights indicate that when the decision is down to the pilot, the pilot will always take the responsible decision, taking account of safety factors and not commercial pressures.

"I'm certain that the same applies for our colleagues in Singapore Airlines."

According to a Reuters Nov 2 report angry relatives of victims demanded immediate answers, interrupting news conferences in Taipei and Singapore to rebuke airline executives for leaving them in the dark for hours about the fate of their loved ones.

"Everyone here knows who the dead are but we were still crying back in Singapore and up till now, we know nothing. You owe us an explanation!" a woman shouted at Cheong Choong Kong, SIA chief executive officer and deputy chairman, in Taipei.

At Singapore's Changi Airport, a distraught man interrupted a news conference by SIA spokesman Rick Clements.

"Tell the press the true story. Don't hide any more," said Tan Yin Leong, whose brother Tan Yip Thong died in the crash.

"Are people's lives more important or SIA's reputation?"

Investigators, who found the black boxes on Nov 1, were looking into whether it took off from a parallel runway that was closed for repairs and hit construction equipment. Much of the wreckage from the plane rests on the closed runway.

Clements has dismissed this, saying the plane used a well-lit runway.

A Taiwan aviation investigator said lights on a taxiway to the closed runway were on.

Lights on the taxiways to both runways were on because they were controlled by the same switch, but it was unclear whether lights on the closed runway were working, investigator Kay Yong said. Those lights were controlled by a different switch.

"We think the lights are an important factor. We are not saying it caused anything. What I am saying today is only factual information. We are not at the analysis stage," said Yong, managing director of the cabinet's Aviation Safety Council.

Authorities have not ruled out whether the aircraft struck an object on the runway, or crashed because of the weather.

Government aviation investigator Chou Hsien-tsan said the plane struck one or two excavators parked near the runways. Both showed signs of damage, but it was not yet clear whether this occurred before or after the crash.