SYDNEY - Torrential rains pummelled Australia's southeast on Friday, dumping almost a month's worth of rainfall on Sydney and triggering flood warnings, with authorities urging people to avoid non-essential travel and stay indoors.

Sydney, home to more than 5 million people, received 111mm (4.4 inches) of rainfall over the 24 hours to Friday morning, data at Australia's Bureau of Meteorology showed, just shy of mean rainfall of 121.5mm for the month of April.

Rains could intensify through Friday with up to 200mm expected in some regions before a coastal trough drifts east towards the Tasman Sea on Saturday, the weather bureau said.

"This is a significant weather event ... it is most important that you don't take unnecessary risks at the moment," New South Wales State Premier Chris Minns said during a televised media conference.

The heavy rains damaged rail equipment at a major train station in Sydney, delaying morning commuters.

Emergency crews in New South Wales received more than 500 calls, and seven people were rescued from flood waters as warnings were issued for several rivers in the east.

Warragamba Dam, which supplies 80% of Sydney's water supply and is currently at around 96% of capacity, could spill over on Monday after the storm eases, officials said.

(Reporting by Renju Jose in Sydney; Editing by Tom Hogue)