By Stefanno Sulaiman and Gibran Naiyyar Peshimam

JAKARTA (Reuters) -The United States has agreed in principle to exempt Indonesian exports of cocoa, palm oil and rubber from President Donald Trump's tariff of 19% imposed since August 7, the Southeast Asian nation's chief tariff negotiator said on Tuesday.

The exemption will take effect once both sides reach a final pact, but no timeline was set as the U.S. was busy in tariff talks with other countries, Airlangga Hartarto, who is also the chief economic minister, told Reuters in an interview.

Also figuring in tariff talks was discussion of a potential U.S. investment in fuel storage in Indonesia, together with its sovereign wealth fund Danantara and state energy firm Pertamina, Airlangga said.

"We are waiting for their response, but during the meeting, basically, the principle (exemption) has been agreed for products not produced in the U.S., such as palm oil and cocoa and rubber ... it will be zero or close to zero," he added.

The region's largest economy was among the first nations to strike a tariff deal with Trump in July, but Jakarta ended up facing the same rate as some other countries, such as Thailand and Malaysia, and just below Vietnam's figure of 20%.

During the talks, Indonesia offered billions of dollars worth of investment in the United States and purchases of American crude, LPG, planes and farm products. It also promised zero tariffs on almost all American goods entering its market.

(Editing by Gayatri Suroyo; Editing by Clarence Fernandez)