TWO men were killed when they were engulfed in a fireball while working inside a 200ft high steel factory chimney.

The men were on a cradle dismantling the tower at Carnaud Metalbox Food UK in Chew Moor Lane, Westhoughton, when an explosion sent flames rocketing up the inside of the chimney.

The cause of the tragedy was being investigated by forensic scientists today.

But one theory is that equipment being used by the workmen, both from Nottingham, ignited a build-up of flammable chemicals. The substances are thought to be either paint or lacquer.

Two other men suffered minor injuries and were treated at the scene but it is not known whether they were contractors or staff employees.

The fireball blasted through the tower as the men were half-way up.

The men, who had been contracted to dismantle the tower by Nottingham-based demolition company Churchills, were working their way down the chimney when the fireball erupted.

Witnesses said flames leapt 30ft into the air and the fire sent a huge pall of smoke into the sky which could be seen for miles around.

It is not yet known whether the men died from severe burns or injuries suffered as the result of a fall. A post-mortem examination was due to be conducted this afternoon.

People living nearby saw the flames and ran out of their homes --unaware that two men had been killed. The news has shocked residents and local councillors.

Cllr Jo Worthington, Mayor of Westhoughton, said: "It is terrible news -- and it will be a shock to the community today.

"My heart goes out to the families of these two men, especially as they are so far away from home."

Witnesses also spoke of the moment they saw the tower explode into flames.

David Lee, aged 44, from nearby Wayfaring, said debris was spewing from the chimney for 30 minutes after the fire.

Mr Lee said: "It was horrendous, absolutely horrendous.

"We just thought the chimney was on fire but to hear that two men have died is absolutely horrific. The flames were also coming out from the side of the tower. They were high and intense."

Fire crews from Hindley, Atherton and Bolton were called to the scene just after 5pm last night.

The site around the chimney was immediately sealed off as firemen battled for up to 30 minutes to bring the fire under control. The identities of the victims have not yet been revealed. Police were last night attempting to contact their families.

A Greater Manchester Police spokesman said: "We are treating the tragedy as a workplace accident."

The company employs around 130 people and has produced metal food cans at the site for the past 46 years.

Steve Thomas, a spokesman for the Carnaud Metalbox Food UK, said: "The mood here today is very sombre and sad. We cannot really add too much at the moment but we can confirm the men were killed when they were working on the plant chimney. Our thoughts today are with all their families as the investigation continues."

A joint investigation by the Health and Safety Executive, the Police and the Fire Service was started late last night and forensic teams worked throughout the night.

Dave Lewis, Assistant Divisional Officer for Greater Manchester Fire Service, said paramedics treated people on the ground for shock and minor injuries.

He said: "It is a very tragic accident. There was some kind of explosion and the cradle fell from some considerable height to the bottom."