SHANGHAI, Aug 23 (Reuters) - China"s top anti-corruption watchdog is investigating the party secretary of Hangzhou, Zhou Jiangyong, for serious violations of party discipline and national laws. The Central Commission for Discipline Inspection announced the probe in a statement published on Saturday. It did not publish further details about the investigation. Zhou became Hangzhou"s party chief in May 2018 and previously held positions in charge of development zones in the cities of Ningbo and Zhoushan, all of which are in Zhejiang province, state media said.