Liberia has denied claims by the Ivorian Government that Liberian fighters have become involved in the conflict in the Ivory Coast.

It has not been the policy of this government to declare war on our neighbours Daniel Chea, Liberian defence minister

The Ivorian Government has blamed Liberian mercenaries for an attack on the village of Neka, saying they were bent on looting.

People fleeing the area say that many people have been killed.

Rebels from the Ivorian Patriotic Movement of the Far West (MPIGO) said they attacked the village and were marching towards the key port of San Pedro, opening a new front in the four-month conflict.

Meanwhile, France has demanded an explanation from the government after a helicopter gunship crossed a ceasefire line with a separate rebel group, killing 12 civilians.

Many hundreds of people have been killed and tens of thousands displaced since 19 September when the Ivory Coast Patriotic Movement (MPCI) first attempted to overthrow President Laurent Gbagbo.

Ivory Coast, the world's largest cocoa-producer, had been seen as an island of peace and stability in war-torn West Africa.

Following attacks on foreigners in government-held areas, there are fears that neighbouring countries could be dragged into the conflict.

White mercenaries

Aminata, an eyewitness who escaped from the scene of the attack on Neka, said: "There were a lot of dead, they killed lots of people.

"We saw the bodies."

The village is 200 kilometres (120 miles) south of previous fighting in western Ivory Coast.

Other civilians said they had seen loyalist troops backed by helicopter gunships and white mercenaries heading for the new front line, according to Reuters news agency.

They also said that many of the fighters involved in the attack on Neka had come from across the border, in Liberia.

But the Liberian Defence Minister, Daniel Chea, denied the allegations.

"It's not true," he told the BBC Focus on Africa programme.

"Liberia, as Sierra Leone before, has become an easy pick.

"Our only involvement in Ivory Coast is our own interest in that country because we share the flight."

Thousands of people - Ivorians and Liberians - have recently fled to Liberia to escape the fighting in western Ivory Coast.

"It has not been the policy of this government to declare war on our neighbours," Mr Chea said.

"Our policy is to work with Ecowas [Economic Community Of West African States] to find a solution."

Retaliation

The French military says government helicopter gunships on Tuesday attacked the lakeside fishing village of Menakro, about 50 km (30 miles) north of the ceasefire line agreed with the MPCI in October.

The rebels want to overthrow President Gbagbo

"France considers this violation of the ceasefire accord to be intolerable ... and will ask Ivory Coast's authorities for explanations. The ceasefire must be respected by all," said a foreign ministry statement released in Paris.

The BBC's Paul Welsh in Ivory Coast says this is the strongest rebuke by the French since the war began.

Former colonial power France has some 2,500 troops in Ivory Coast in a bid to enforce the fragile ceasefire.

Ivorian army spokesman Colonel Jules Yao Yao told the BBC that the raid was in retaliation for a rebel attack on government forces on Tuesday.

He said the French forces had been warned in advance that the government would be striking back.

All rebel groups demand President Laurent Gbagbo's resignation and fresh elections.