President Yoon Suk Yeol on Wednesday ordered the office of the presidential secretary for civil service discipline to conduct a thorough investigation into the officials mired in corruption allegations over solar power projects, part of the previous Moon Jae-in government's push to increase the share of renewable energy in Korea's energy mix.

"President Yoon ordered a thorough investigation into the entire decision-making line involved in the solar projects at the time," said Yoon's spokesperson, Lee Do-woon.

On Tuesday, the Board of Audit and Inspection raised allegations that some public officials and heads of local governments had colluded with private companies and fabricated documents to receive state subsidies.

Gunsan Mayor Kang Im-jun, who has been the mayor of the city since 2018, allegedly selected as the preferred bidder for a solar power project a solar panel company led by a fellow high school alum in 2020. In a different case, several officials from the Ministry of Trade, Industry and Energy at the time allegedly colluded with a private company in a solar panel project in Taean between 2018 and 2019, as they were found to be later hired by the company and affiliated companies.

While it started its audit into solar power projects that received subsidies under the Moon administration in October last year, the BAI has also been investigating 250 employees from eight public institutions who allegedly conducted solar energy businesses without reporting their personal interests in them, using undisclosed internal information to obtain certain benefits or advantages.

The BAI said it has asked the prosecution to investigate further 13 people, including former executive-level officials of the central government and heads of local governments.

An official from the presidential office said that depending on the results of the civil service discipline secretary's investigation, disciplinary action may follow if clear violations of the law are detected.

Promoting renewable energy businesses across the country was Moon's key energy policy.