East Timor joined the Association of South East Asian Nations (Asean) bloc as its 11th member state on Sunday, after 14 years of campaigning.

Malaysian Prime Minister Anwar Ibrahim, whose country currently chairs Asean, said East Timor's accession "completes the Asean family – reaffirming our shared destiny and deep sense of regional kinship".

"Within this community, Timor-Leste's development and its strategic autonomy will find firm and lasting support," Anwar told an Asean summit in the Malaysian capital of Kuala Lumpur.

East Timor, also known by its Portuguese name Timor-Leste, is the youngest country in the region, having gained independence from Indonesia in 2002 after 24 years of occupation.

President Jose Ramos-Horta has long campaigned for Asean membership, and an application was first submitted in 2011 during his first term.

Prime Minister Xanana Gusmao said it was a historic moment for his country, with a new beginning that would bring "immense opportunities" for trade and investment.

"For the people of Timor-Leste, this is not only a dream realised, but a powerful affirmation of our journey," Gusmao said in a speech.

"Our accession is a testament to the spirit of our people, a young democracy, born from our struggle," he said, adding, "This is not the end of a journey."

The signing of a declaration on East Timor's admission on Sunday is also seen as one of the crowning achievements of Malaysia's Asean chairmanship.

East Timor was granted observer status to the regional body in 2022 but its full membership was delayed by various challenges.

The country continues to grapple with high levels of inequality, malnutrition and unemployment.

It remains heavily reliant on oil, with little diversification into other sectors.

It also faces challenges in infrastructure development and human resource capacity, seen as critical for effective participation in Asean's economic community.

In September, thousands of student-led protesters demonstrated against a multi-million dollar plan to purchase Toyota Prado SUVs for each of the country's 65 members of parliament and lifetime pensions for former MPs.

Demonstrators and police clashed for two days, before the parliament cancelled the vehicles' procurement.

The parliament has also bowed to public pressure over MPs' pensions.

Asean began as a five-member bloc in 1967 and has gradually expanded, with Cambodia the most recent addition in 1999. (Agencies)