By Madeline Chambers and Estelle Shirbon

ABUJA, Feb 14 (Reuters) - British Foreign Secretary Jack Straw warned the warring parties in Sudan's Darfur region on Tuesday that Britain would back new sanctions against them unless they got serious about striking a peace deal.

Straw blamed negotiators from the Sudanese government and three Darfur rebel factions for talking peace while escalating violence on the ground -- echoing frustration expressed by the African Union (AU) and the United Nations.

"Progress in the talks has been far too slow," Straw told delegates on a visit to the talks in the Nigerian capital.

Rebels from the Sudan Liberation Army (SLA) and the smaller Justice and Equality Movement (JEM) took up arms in early 2003 over what they saw as marginalisation by the government. They say Khartoum backed proxy militias to fight the rebels.

The conflict has killed tens of thousands of people and driven more than two million into refugee camps.

After a lull, violence escalated anew in late 2005 and the United Nations has described an increasingly chaotic situation where rival rebel factions, bandits, pro-government militias and unidentified gunmen kill, rape and loot with impunity.

"The international community is not going to allow those individuals who are responsible for gross human rights violations or blocking the peace process to escape the consequences of their actions," Straw told the delegates.

"We know who these people are," he said, adding that Britain would not hesitate to put forward new names for inclusion on a list of people from both sides already being considered by the U.N. Security Council's Sanctions Committee.

ADDITIONAL U.N. SANCTIONS

He said Britain would not rule out additional U.N. sanctions against the government or the rebels if they failed to progress.

The head of the government delegation, Majzoub al-Khalifa, dismissed the threat of sanctions, saying that Sudan would prosecute human rights violators in its own courts -- a standard line from Khartoum.

"We are not waiting for the Security Council or for the international community. It is our duty," he told Reuters.

The rebel factions said they were unconcerned about possible sanctions as the government was responsible for the violence and for blocking the peace talks by not making a good offer.

However, Straw said Britain's view was that the rebels were most guilty of recent attacks.

He also said that if they chose not to strike a peace deal, the international community would consider alternatives that would leave some of them with smaller roles.

The AU, which has about 7,000 peacekeepers in Darfur and is the main mediator in the peace talks, says it still hopes the current round, the seventh, will yield a settlement. But it calls progress "agonisingly slow".

Straw said Britain would give the AU a further 1 million pounds ($1.74 million) for its work in the peace process.

The three main areas of negotiation are power-sharing, wealth-sharing and security. While some progress has been made on wealth, delegates say the other two areas are deadlocked.

One of the main problems is infighting among the rebels, which showed no sign of abating after Straw's speech.

Abdel Wahed Mohammed al-Nur, leader of one of the factions of the SLA, told Reuters he would cease all coordination with the rival faction led by Minni Arcua Minnawi because of two incidents at the weekend. He said Minni's forces had killed two of his people and kidnapped six in Darfur.

The chief negotiator for the Minni faction denied this.