A sinkhole the size of a backyard swimming pool has opened up in a street near Australian Prime Minister Malcolm Turnbull's Sydney harbourside mansion.

A gas line ruptured on Wentworth Street in Point Piper when a large part of the footpath collapsed and washed away today after about half a month's worth of rain pelted the city yesterday.

Rainwater could be seen streaming into the sinkhole, undercutting the earth underneath the road at the edge of the hole, which is a block away from Turnbull's home.

As emergency crews worked to limit the spread of the crater, local resident Kirsty Mirzikinian and her personal trainer watched in disbelief.


Mirzikinian, whose home is opposite the sinkhole, told reporters she was in shock.

"My personal trainer has come, my electricity is off and now I don't know what to do," Mirzikinian said. "I can't believe there's a hole just right across the street from my house, this doesn't normally happen."

Mirzikinian said she smelt a gas leak yesterday. "We did smell a gas leak in the afternoon and the guys came and they were banging around, breaking down the concrete," she said. "Basically we woke up and it was like this."