In a Dunkirk-style effort, private boat owners and surf lifesavers joined efforts to rescue people stranded on beaches as bushfires swept Sydney’s Royal National Park.

An emergency warning for the two out of control fires south of Sydney was downgraded to a watch-and-act alert on Saturday evening.

A number of visitors stranded by fire had been rescued on beaches adjacent the national park, NSW Rural Fire Service said.

“There are a number of boats being utilised by surf lifesavers, NSW Police Force and some private citizens that are picking some people up from beaches in the area,” RFS spokesman James Morris told AAP earlier in the evening.

Mr Morris said those caught up in the drama had found the park’s many beaches to be the best places to take cover.

“They’re providing the best protection given the fact a lot of the escape routes are through the middle of the bushland which isn’t safe at the moment given the intensity of that fire.”

More than 100 firefighters battled the blaze on Saturday evening, supported by water bombers and aircraft.

A billowing column of dense smoke swells above the Royal National Park inferno. AP/Ben Rushton

While 200 people were escorted from popular tourist spot Wattamola Beach to Bundeena by RFS crews, Mr Morris said a large number were still being observed on walking tracks by circling planes.

“There is still a significant number of people in there,” he said.

Given the limited mobile coverage in the Royal National Park, Mr Morris said many people in the bushland were “unlikely” to have received emergency text warnings.

Embers are believed to have caused a second fire nearby on Sir Bertram Stevens Drive at Flat Rock.

All roads into the Royal National Park were closed and motorists advised to avoid the area, while people in southwestern Sydney and the Illawarra have been advised to be wary of smoke.

Further south, near Bowral, rural properties in the Alders and Crees Road areas in Bannaby may come under threat from a grassfire, the NSW Rural Fire Service says.

The 634-hectare blaze is at watch-and-act alert level with firefighters and an aircraft on scene to try to slow its spread.

A watch and act alert has also been issued north of Tamworth, where there’s an out of control 3500-hectare fire. The RFS is concerned isolated rural properties may be threatened 10km southwest of Bundarra.

Firefighters are conducting backburning operations in the area and the Newell Highway is shut between Narrabri and Coonabarabran and likely to remain closed on Saturday.

Aircrane working to slow spread of one of the fires in the Royal National Park. #NSWRFS pic.twitter.com/v1SSStht76

— NSW RFS (@NSWRFS) January 20, 2018

East of Canberra, firefighters from the ACT were sent into NSW to protect houses threatened by another bushfire in the Southern Tablelands.

Three heavy tankers, backed up by smaller crews, were deployed to the 274 hectare Braidwood blaze on Saturday morning after it burned through the night.

“Their objectives are to protect properties, attack and contain the main fire and contain spot fires,” the ACT Emergency Services Agency said.

Fire crews remain at rural Victoria bushfires

Meanwhile, firefighters are focusing their efforts on two large bushfires triggered by lightning in rural northwest Victoria.

Crews are also keeping an eye on the weather, with the potential for thunderstorms and further lightning strikes during Saturday afternoon and overnight into Sunday.

The blazes — measuring 141 hectares and 1271 hectares — are burning in the remote Big Desert area near the South Australian border and are not yet under control.

A further 15 fires are contained in other areas across Victoria.

“The response from the community has been really good,” a State Control Centre spokesman told AAP.

“Most of the fires have been small scale and we’ve been able to respond quickly.”

A total fire ban will remain in place for the Mallee district on Sunday, with temperatures in the area once again set to rise above 40.

Uncontrolled bushfire still burning in South Australia

A bushfire continues to burn uncontrolled in a conservation park in South Australia’s southeast with locals and tourists warned not to enter the area.

The Country Fire Service says the blaze in the Karte Conservation Park is burning in scrub and fire crews will be working on the fire all of Saturday.

Their efforts will centre on preventing the blaze from reaching Mootatunga in the state’s Mallee region.

It was sparked on Friday, prompting a watch and act message.

“Crews will be back burning to establish control lines and will continue to be working on this bushfire all day,” the CFS said.

Locals have been urged to follow their bushfire survival plans.

Meanwhile, firefighters continue to battle with a bushfire that’s burnt about 20,000 hectares in the Pilliga Forest between Coonabarabran and Narrabri.