In the regional capital Dili, hundreds of pro-Jakarta supporters attended a rally to persuade voters to choose to stay part of Indonesia.

"We are the same land, we are part of Indonesia, we need to go back to our motherland," said Domingos Soares of the United Front for East Timor Autonomy.

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The referendum will ask East Timorese whether they want independence, or wide-ranging autonomy within Indonesia.

The crowd, many of them wearing small red and white Indonesian flags tied round their heads and T-shirts printed with "Autonomy, Yes", sang songs of support for Indonesia.

Scores of uniformed but unarmed members of pro-Indonesia militias mingled with the crowd.

The United Nations, which is supervising the 30 August vote, said the peaceful rally boded well for the campaign.

The Independence camp fears attacks

Violence has erupted between the rival groups in recent weeks and many of the incidents have been blamed on the militias, which have received Indonesian backing.

UN personnel have been deployed to maintain security.

But pro-independence activists said they would not hold similar rallies because of safety fears. Instead they will take their campaigning door to door.

Independence movement spokesman David Ximenes added: "Most East Timorese have wanted a separate state since 1975. We don't need to hold rallies."

No violence

At the official campaign opening ceremony at the UN headquarters in Dili, both sides of the political divide stressed their commitment to a peaceful referendum.

About 450,000 have registered to vote on 30 August

UN special envoy for East Timor Jamsheed Marker said Saturday was an "important if not historic day".

"What you have embarked upon today, the implementation of the... process of discussion, debate and campaigning in a civilised manner, of putting peace and unity above all party considerations, is the essence of democracy," he told leaders of the two sides.

Last week both camps signed a code of conduct under which they promised not to use violence, intimidation or inflammatory language in the run-up to the referendum.

The campaign will end on 27 August, and will be followed by a two-day cooling-off period before the vote is held.