Months after dropping them from his Cabinet, Indonesian President Joko Widodo has reinstated former ministers Ignasius Jonan and Arcandra Tahar to senior posts.

Mr Arcandra was appointed Energy and Mineral Resources Minister during a reshuffle in July, but held the post for only 20 days before stepping down after it was discovered he was an American citizen.

Mr Jonan, who was dropped as Transportation Minister in July, will now helm the Energy and Mineral Resources Ministry, with Mr Arcandra as his deputy.

Mr Jonan is a newcomer to the resources sector, a major contributor to the state budget, while Mr Arcandra is a former United States oil and gas executive.

Coordinating Maritime Affairs Minister Luhut Binsar Pandjaitan, who was asked to step in as an interim energy and mining minister, has been relieved of the portfolio.

Mr Joko lauded Mr Jonan and Mr Arcandra as "professional figures who are right, brave and have the potential to carry out large-scale reforms" in the ministry. He told reporters after their inauguration yesterday that his decision to appoint them was based on "the issue of management".

"I'm sure both figures have the competence although I know they're stubborn and like to go to the field. This is not an easy task but I'm certain they both can resolve the problems (in the ministry) and have good teamwork," the President said.

Mr Jonan was the chief executive of state-owned railway company Kereta Api Indonesia before he was appointed transportation minister in 2014. He was dismissed in July because he was seen as a stumbling block to the President's high-speed railway project between Jakarta and Bandung.

Mr Arcandra lived in the US for 20 years. Indonesian law does not allow dual nationality. His Indonesian citizenship has since been reinstated.

Asked by reporters if his appointment as deputy was a demotion, he said it was "the best decision" made by Mr Joko, and he will "fully support" the new minister. "I am ready to serve wherever and whenever."

Analysts said their reappointment to the Cabinet was a positive move as they are considered competent. Political analyst Arbi Sanit told The Straits Times: "The President has corrected his previous errors with the reappointment. Mr Jonan returned as a minister with his experience in the government, and Mr Arcandra had to pay for his mistake by being the deputy."