At the time, East Timor was ruled by Portugal, although it was clear that Lisbon would soon relinquish its colony.
East Timor was later annexed by Indonesia and gained full independence only in 2002.
At a summit in the Cambodian capital Phnom Penh this week, ASEAN said East Timor would be granted observer status at high-level meetings of the bloc as it formulates a "roadmap for full membership".
He served as the country's first foreign minister, prime minister from 2006 to 2007, and president from 2007 to 2012, during which time he survived an assassination attempt by rebel soldiers.
East Timor celebrated 20 years of independence this year, but the country of 1.3 million people is heavily dependent on dwindling reserves of oil and gas.