An appeals court on Wednesday upheld an acquittal of a former Navy chief for corruption in a deal to supply parts of the country's indigenous salvage ship, citing lack of evidence.

The Seoul High Court found the retired Adm. Hwang Ki-chul, who served as the Chief of Naval Operations from 2013 to 2015, not guilty of allegations that he pressured his subordinates to forge a document in 2009 to help a firm win the contract.

Prosecutors suspected that he made them manipulate a quality assurance document for a sonar system built by a parts supplier for the country's first domestic salvage ship. The supplier was introduced by a friend of the then-Chief of Naval Operations Chung Ok-geun.

Hwang, who was in charge of the nation's project to build the Tongyeong at the Defense Acquisition Program Administration, was suspected to have played a role in the underhand dealings in order to get promoted.

The appeals court, however, said the defendant did not get involved in writing the report and the crime motive was unclear.

"To say the malpractice was intentional, there should be an explicit motive but what the prosecutors submitted as Hwang's motive was not convincing and lacked sufficient proof," the court said.

The 3,500-ton Tongyeong was found to be fraught with problems and failed to participate in rescue operations in a ferry tragedy in April 2014 that killed more than 300 people. (Yonhap)