Troops shoot man dead and fire teargas in bid to contain growing unrest and looting

Tear gas was widely used by troops enforcing a dusk-to-dawn curfew aimed at preventing people from ransacking markets and stores for food, electronic equipment and other goods.

With the death toll from the 8.8 magnitude quake now at 708 and expected to rise further, president Michelle Bachelet called for international help to confront what she described as "an emergency without parallel in Chile's history".

The UN said it would begin rushing aid deliveries to the country following the request, but aid workers have warned that further aftershocks are possible, and pointed to a number of "silent areas" that have no contact with the outside world.

As British charity workers began to help plan the recovery process, Prime Minister Gordon Brown sent a message of sympathy to Ms Bachelet, describing the events as a "truly devastating catastrophe".

The earthquake, the seventh most powerful on record, struck at 3:45am on Saturday, affecting an estimated 1.5 million Chileans. With subsequent aftershocks of up to 6.9 magnitude, thousands of people have been forced to take refuge in tents and makeshift shelters.

Shortages of drinking water and food have worsened the effects of the disaster, while power cuts have slowed relief efforts.

Elisabeth Byrs, a UN spokeswoman, said Chile had requested field hospitals with surgery facilities, mobile bridges, communications equipment, kitchens, and disaster assessment and co-ordination teams.

"We are prepared to provide assistance," she said. "It could be quite fast, given that our experts are on standby and were alerted in the region."

The scale of the destruction caused by giant waves triggered by the quake became clear yesterday, with coastal towns and villages badly hit.

In the town of Constitucin alone about 350 bodies were found, and a public gym became a makeshift morgue.

Defence minister Francisco Vidal has admitted the country's navy made a mistake by not issuing a tsunami warning immediately after the earthquake, a move that could have helped coastal residents flee to higher ground sooner.

Police in Concepcin said 55 people had been arrested for violating the curfew, with around 10,000 troops dispatched to maintain order. Some looters were caught using long tubes of bamboo and plastic to siphon petrol from underground tanks at a closed petrol station. Looting was also reported in the capital, Santiago, and in the Maule region.

Elsewhere in Concepcin , rescuers armed with thermal detection devices strove to save victims trapped in a collapsed apartment building, with 25 survivors taken out so far, along with eight bodies. "There were answers to our knocks. We are not sure how many people are there, apparently three," said firefighter commander Juan Carlos Subercaseaux.

Concepcin's mayor, Jacqueline van Rysselberghe, warned

: "We need food. We are without supplies, and if we don't resolve that we are going to have serious security problems."

A five-strong team of emergency response experts from Oxfam, including water engineers and logisticians, was due to arrive in Chile yesterday to help the government.

Aid experts said Chile was in a better position to cope with the aftermath of the disaster than Haiti, as it is a more developed nation. However, charities have warned that communications and access problems have hampered workers' efforts to reach people needing help.

The British Red Cross, which has received reports of "significant damage" to roads, bridges, and buildings, has launched an appeal in response to the quake.

A spokesman for the Disasters Emergency Committee said it would continue to monitor the situation before deciding whether to launch an appeal.