Moon Jae-in, a leading presidential candidate from the opposition bloc, on Tuesday published a book on his campaign pledges, taking further steps to generate support ahead of this year's election.

The publisher said the book, titled "The Republic of Korea asks," is about the blueprint of Moon's vision for South Korea, providing ways to tackle various challenges facing the country.

The 360-page essay also delivers Moon's stance on controversial policies promoted by impeached President Park Geun-hye, including the deployment of an advanced US missile defense system in the country.

"(The decision on the Terminal High Altitude Area Defense
battery) was made unilaterally by President Park Geun-hye. The issue should have been thoroughly reviewed at the National Assembly as it calls for a parliamentary ratification," Moon claimed in the book.

"The THAAD system could spark a competition among powers on the Korean Peninsula once again," Moon also said, adding the issue should be reviewed in a bigger picture instead of only focusing on North Korean nukes.

On his biggest potential rival, ex-UN Secretary-General Ban Ki-moon, Moon said the former diplomat has been enjoying privileges of the established, and claimed he may be less keen in constructing a new South Korea.

Moon also said Park, along with her conservative predecessor Lee Myung-bak, should be held responsible for abusing powers for personal interests.

The potential candidate also pledged to have the prosecutor's office hand over more authority to the police in regards to investigations to promote balance in law enforcement. (Yonhap)