He calls on China to provide a level playing field for American businesses as he begins a visit aimed at resolving a raft of contentious issues
The Seoul Metropolitan Police Agency said officers were searching for him around Sungbuk-dong, a district in northern Seoul, where his phone signal was last detected.
His daughter reported him missing at 5:17 p.m. (0817 GMT) and said his phone was off, the police said.
Park, who has been the mayor of Seoul since 2011, is seen as a potential presidential hopeful for the liberals in the 2022 presidential elections.