SEOUL, Jan. 27 (Yonhap) -- Former U.N. Secretary-General Ban Ki-moon met with a former opposition leader on Friday, multiple sources familiar with the meeting said, the latest in a series of his efforts to join forces with the opposition bloc for his presidential bid.
Ban held a closed-door meeting with Sohn Hak-kyu for about an hour at a restaurant in Seoul, the sources said.
The two are believed to have shared the need for revising the Constitution, though they were reportedly at odds over details.
Ban recently called for a constitutional revision before the presidential election in a way that would empower the prime minister to be in charge of domestic affairs.
In South Korea, the prime minister is the second highest position after the president, but the job has been a largely ceremonial role as power is concentrated heavily in the president.
South Korea has revised the Constitution nine times since 1948 when it came into being.
South Korea introduced the single five-year term presidency in 1987 after decades of autocratic rule by military-backed presidents. The system was primarily aimed at keeping the president from attempting to hold on to power through illicit means.
Sohn is said to have called for a transfer of power led by reformists in a clear signal that he would not join hands with Ban in case the former U.N. chief works with the ruling Saenuri Party or other conservative party.
"We should stand on the side of reform," Sohn said, noting that the era of a conservative government is gone.
South Korea has been ruled by conservative administrations since 2008 when President Lee Myung-bak began his term, ending a decade of liberal leadership.
Sohn said he told Ban that the former U.N. chief should be more clear about his political line and policy.
Ban, who has described himself as a liberal conservative, did not answer Sohn's proposal, according to Sohn.
Sohn quit the Saenuri Party's predecessor in 2007 before joining the main opposition party. Currently, he does not hold any party affiliation after he left the main opposition Democratic Party.
Also Friday, Ban met with police officers and firefighters in an apparent move to give them pep talks and promote his presidential bid.
Ban has met with various politicians while making visits to different areas of the country after returning home earlier this month from New York where he served as the U.N chief.
Ban is the second most favored figure among all presidential hopefuls, next to Moon Jae-in, a potential rival from the Democratic Party.