The Observatory on Saturday issued the red rainstorm warning at 9.10 am as a south-west monsoon brought heavy showers and thunderstorms to Hong Kong. It said whether the black rainstorm warning signal needs to be issued depends on the development of the band of thundery showers.

Rain is particularly heavy in the Eastern district of Hong Kong Island and Sai Kung with more then 70 millimetres of hourly rainfall.

The government asked members of the public to report any street flooding to the Drainage Services Department and schools that are in session will continue until the end of school hours.

Police have so far received one report of flooding on Tseung Kwan O Tunnel Road.

The Observatory had earlier issued the amber rainstorm warning at 6.50 am.

The latest warnings come five days after Hong Kong saw its first black rainstorm warning of the year.