Public transport slowly started to get back to normal in many parts of Hong Kong on Friday, despite the widespread flooding brought by record rainfall overnight.

The Black Rainstorm Warning remained in effect, however, many hours after it was issued late on Thursday night.

Bus services gradually resumed from 9am, but firms warned that extreme weather conditions were still posing a significant challenge in some areas.

"Owing to the heavy rain and severe flooding in various locations across the region, a number of KMB and LWB routes will be diverted or suspended," KMB said.

Citybus warned that it could take longer to get buses back on the road in places including Stanley, Wong Chuk Hang and Tseung Kwan O.

The MTR saw some improvement before lunchtime. There were still longer waits than usual between trains on the East Rail, Kwun Tong, Tsuen Wan, Island and Tuen Ma lines, but other lines were back to normal.

The most serious disruption continued to be seen on the Kwun Tong Line, which was still closed between Shek Kip Mei and Choi Hung after Wong Tai Sin Station was flooded.