UPDATE 4-Seoul mayor found dead after leaving message 'like a will'

(Updates with details)

By Hyonhee Shin

SEOUL, July 9 (Reuters) - Longtime Seoul City Mayor Park Won-soon was found dead, police said on Friday, after his daughter reported him missing saying he had left a message "like a will".

The mayor's body was found at Mt Bugak in northern Seoul around midnight, near where his phone signal had last been detected, the Seoul Metropolitan Police Agency said. The agency did not give a cause of death.

His daughter reported him missing at 5:17 p.m. (0817 GMT) and said his phone was off and that he had left a message "like a will", the Yonhap news agency reported. Hundreds of police took part in a search for the mayor.

Yonhap said a former secretary of Park filed a complaint on Wednesday over alleged incidents of sexual harassment.

The city's police did not respond to Reuters' calls seeking comment, but said in a statement that it would investigate the cause of his death.

As mayor of the city of nearly 10 million people, Park was one of South Korea's most influential politicians and played a high-profile role in its response to the coronavirus pandemic.

He was seen as a potential presidential hopeful for the liberals in the 2022 presidential elections.

The discovery of his body followed a hours-long night search in one of the most mountainous and scenic parts of Seoul just a few minutes from the heart of the metropolitan capital, involving hundreds of police using drones and dogs.

Park left the mayor's official residence at around 10:40 a.m. (0140 GMT) on Thursday, wearing a black hat and a backpack, having cancelled policy meetings scheduled for the day, according to multiple local reports.

CAMPAIGNER FOR WOMEN'S CAUSES

Formerly a prominent human rights activist and lawyer, Park has been the mayor of Seoul since 2011, pursuing a slew of policies promoting gender equality.

As a lawyer in the 1990s, he won one of South Korea's earliest cases on sexual harassment, and strongly advocated for the cause of "comfort women," those who were forced to work in Japan's wartime military brothels before and during World War Two, when Japan occupied Korea.

Park also praised women for their courage after a series of women accused powerful politicians and policymakers of sexual wrongdoings amid the #MeToo movement in 2018.

"The resolve of individual heroines is not enough. I think we need social solidarity," he said, calling for support for the movement.

He also played a vocal role in the massive candlelight demonstrations that helped lead to the ousting of former President Park Geun-hye in 2017. (Reporting by Cynthia Kim, Hyonhee Shin, Sangmi Cha, and Josh Smith Editing by Alex Richardson, Nick Macfie and Frances Kerry)