DILI - East Timor President Jose Ramos-Horta was shot and critically wounded at his home in Dili on Monday in an assassination attempt by rebel soldiers that analysts said could spark renewed violence and political chaos in the tiny nation.

Prime Minister Xanana Gusmao escaped injury in another attack also on Monday morning, officials said.

Australia pledged to send more troops to Asia's youngest nation after the apparently coordinated attack on East Timor's two most famous independence figures.

Residents in Dili reported the capital appeared calm and Gusmao said Ramos-Horta was in stable condition after the attack in which a key rebel leader was killed.

The president, who shared the 1996 Nobel Peace Prize with compatriot Bishop Carlos Belo for their nonviolent struggle for East Timor's independence from Indonesian occupation, was operated on by an Australian military medical team in Dili before being flow to Darwin in northern Australia for treatment.

"This is a serious attempt on a democratic state," Gusmao told a news conference.

An Australian medical spokesman said Ramos-Horta was in a critical but stable condition.

"He has suffered major wounds and he has had massive blood transfusions. They are potentially life-threatening," said a spokesman for CareFlight medical evacuation organisation after Ramos-Horta landed in Darwin.

"He has been placed on full life support, including an induced coma and ventilator to assist his breathing. That is standard procedure."

The former Portuguese colony of almost 1 million people gained independence in 2002 in a U.N. sponsored referendum after more than two decades of brutal Indonesian occupation.

But it has been unable to achieve stability.

Tensions rose this month after rebels loyal to rebel leader Alfredo Reinado, who was blamed for Monday's attacks, fired on Australian troops patrolling near Dili.

"Prime Minister Xanana is going to have to work very hard to ensure the government retains its cohesion. It's a crisis now," said Damien Kingsbury, associate professor at Australia's Deakin University.

COORDINATED ATTACKS

Australian Prime Minister Kevin Rudd said he was "deeply shocked" by what appeared to be "coordinated attacks aimed at assassinating the democratically-elected leadership".

Rudd said he would visit East Timor later in the week to inspect security after a request from Gusmao.

Australia would send around 200 quick reaction troops immediately to the fledgling nation, along with 50 to 70 police.

New Zealand, which has more than 200 soldiers and police in East Timor, was putting additional troops on standby, New Zealand Foreign Minister Phil Goff said.

International security forces in East Timor, led by around 800 Australian soldiers, had secured key buildings in Dili and increased patrols in the capital and across the country.

Len Notaras at Royal Darwin Hospital, where the president was being treated, earlier told Sky News that Ramos-Horta had been shot in the right side of his chest and in the lower abdomen.

East Timor has been struggling to get back on its feet after the army tore apart along regional lines in 2006.

The factional bloodshed two years ago killed 37 people and drove 150,000 from their homes, with foreign troops needed to restore order between warring neighbourhoods.

Reinado had led a revolt against the government and was charged with murder during the 2006 factional violence.

A Reuters reporter saw the bodies of the two dead attackers and identified one of them as Reinado.

An East Timor soldier was also seriously wounded, a military spokesman said.

The military said attackers in two cars were involved in the early morning raid on the president's isolated home, while Gusmao's car was targetted, one official said.

"No one was wounded but Gusmao's car was damaged by bullets," said the official, adding that Gusmao's family had been taken to a military compound for protection.

Aid worker Mauricio Borges told Reuters Dili appeared calm.

"Dili is safe. There are no riots in the capital. But there is heavy patrolling by the police and military police," Borges said, adding many helicopters were flying over the capital.

Security analyst Alan Dupont, from Sydney think-tank the Lowy Institute, said the shooting would "destabilise East Timor further at a time when they looked to be recovering from the problems of the last 12-18 months."