"Large numbers of firefighters will continue to work into the night to bring the fire under control".
Heathcote Road remains closed between Macarthur Drive and New Illawarra Road while Old Illawarra Road at Barden Ridge has reopened.
"We had some very big fires here in 1994, we lost something like 20 homes", he said.
Police monitor for threats to homes as a bushfire threatens properties in several suburbs on Sunday.
An unspecified number of Menai and Barden Ridge residents left their homes after New South Wales authorities declared a state of emergency as nearly 100 firefighting trucks and 15 aircraft continued fighting back the blaze, Efe news agency reported.
NSW Police on Sunday evening announced a task force had been set up to investigate whether the fire, which began in the vicinity of Leacocks Reserve in Casula, was deliberately lit.
The New South Wales Rural Fire Service said 900 of its personnel were fighting 48 fires in southwest Sydney, near Holsworthy and Menai.
"We don't tolerate this sort of thing".
Conditions on Monday are expected to help the firefighting effort but winds could pick up to 35km/h later in the day.
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"How dare anyone, if they are deliberately involved in lighting fires, endanger our firefighters and also putting all these communities in harm's way".
Local resident Jordan Dodin climbs onto a roof to protect the house from fire in Wattle Grove on Saturday night.
RFS spokesman Greg Allan said some properties had not escaped unscathed.
But high temperatures remain a cause for concern, Rural Fire Service Deputy Commissioner Rob Rogers warned.
A blaze at Menai still continues to burn in a south easterly direction toward Barden Ridge - no homes are at risk but crews are on the ground focused on containing the fire.
"Still quite a hard day ahead (on Monday)", he told the Nine Network.
Over the weekend the blaze was declared an emergency a number of times but was downgraded to watch and act when winds dropped down to around 15 to 25 kilometres per hour.
"I think it's fair to say that it is highly suspicious, in the absence of any other cause like lightning", he said.