JAKARTA, Jul. 18 (Reuters) - Indonesia's outgoing President Joko Widodo will appoint Thomas Djiwandono, the nephew of president-elect Prabowo Subianto and his adviser for fiscal issues, as a deputy finance minister later on Thursday, two sources said.

The sources declined to be named due to the sensitivity of the information.

Djiwandono, the presidential office, the finance ministry, and officials with Prabowo's Gerindra political party did not immediately respond to request for comment.

"This is to ease the transition of government," said one of the sources.

U.S.-educated Djiwandono has been the main spokesperson for Prabowo's fiscal stance, often reiterating the incoming president's commitment to abiding by fiscal rules and keeping the 2025 budget deficit under the legal limit of 3% of gross domestic product.

Financial markets have been paying close attention to Prabowo's fiscal policy after ratings agencies warned fiscal risks will rise due to his costly campaign promises, which include a flagship programme to provide free school meals.

Concerns of rising debt has added to pressure on the rupiah and Indonesian bond prices, though they have since bounced back.

Photo from KOMPAS