The Church of Scientology is surrounded by secrecy and suspicion, and now residents living next door to Scientology's Asia-Pacific headquarters feel they've been locked out of the once-public land, with the property looking more like Fort Knox, and less like a Church.

Scientology describes itself as the world's fastest-growing religion, but residents surrounding the Church's Asia-Pacific headquarters say security in their area is growing even faster.

The Church has been accused of blocking access to the national park. Security gates have been installed which operate 24 hours a day, and the Church plans to distribute swipe cards to residents. All of these security measures were implemented prior to receiving council approval.

The Church of Scientology's Australian headquarters are in Sydney. (A Current Affair)

Lynne Saville, a councilor at Willoughby City Council in Sydney, and a resident in the area of 35 years, says she and her neighbours feel they've been locked out.

"The residents in the area upset about the security measures that have been imposed. The people around here have been very confused and outraged really," Councilor Saville told A Current Affair.

"The neighbours have always had a high sense of ownership about this property, they've used it, they've walked through it, they've defended the creek, done bush regeneration here."

Locals claim they've been locked out of the national park. (A Current Affair)

Before the block belonged to the Church of Scientology, it was the National Acoustic Laboratory, and was Commonwealth land. Walking trails connect the church's site to the adjoining Lane Cove National Park and Blue Gum Reserve, and members of the public have always had access.

"I think it's very unfortunate that the Church are now trying to change very reasonable conditions of consent to which they agreed at the time," said Ms Saville.

The Church of Scientology purchased the land in 2014, on the agreement the Church would continue to allow public access and connect, where possible, with bushland trails.

The church's new security measures were implemented following a murder on the premises. (A Current Affair)

The Church's application to modify their development application was submitted in June 2019.

Council initially recomended refusal on the basis that restricting access to bushland trails would create a 'gated community' and that it would allow 'card only' access to a limited number of people.

However, the Church upped their security in January of 2019, well before their plans were approved by the Sydney North Planning Panel just last month.

Gates will require swipe cards. (A Current Affair)

President of the Friends of Lane Cove National Park, Tony Butteriss, says the new security gates are a potential fire hazard.

"It's really important that people have quick access if there is a fire. The path that comes up through the national park, through the bottom of the Scientology centre, if there's a fire coming through the hill, that could move very, very quickly," Mr Butteriss told A Current Affair.

"If there's any delay, if there's a firefighter or member of the public there and they're delayed at the gate because it won't open or it can't be opened, that could be crucial, they could lose their lives."

Friends of Lane Cove National Park president Tony Butteriss claimed the new gates could be a fire hazard. (A Current Affair)

The area of the property is 35,000 square metres and fits 460 people inside. There are now security gates at Greville Street and Range Street. Both gates require a swipe card to access the park trails. The Church added an extra access point on Millwood Ave for their buses.

As a resident within the area, Mr Butteriss says he doesn't feel he should need a swipe card to access to park trails.

"I'm very much against anybody having to give their personal information to the Church," he said.

Councilor Lynne Saville said people were "confused and outraged". (A Current Affair)

The Church of Scientology refused an on camera interview, but did send A Current Affair a statement, saying "The Church of Scientology has taken the measures to ensure the health and safety of our staff, parishioners and all local residents on our property."

"We are taking extra measures to maintain access for our neighbours and the community to enjoy the nearby National Park and walking tracks," the stateement read.

The increased security by the Church comes after an employee of the organisation was murdered on the premises in January last year.

The Sydney North Planning Panel has since requested the Church of Scientology make a number of changes.

Security intercoms need to be installed at the pedestrian gates, signage saying 'visitors are welcome to enter and enjoy our grounds' will be placed at the main entrance, and swipe cards must be issued to a number of households in the area.

However, the Church can refuse issuing security access cards to any household or person they can prove is a threat.

The Sydney North Planning Panel expect the Church to have implemented their requested changes by early 2020.

Statement from Church of Scientology

The Church of Scientology has worked with the local Council and the Sydney North Planning Panel to agree on safety measures around the Church property and access to local walking tracks.

The security upgrades were done immediately after the tragic death on our property early this year, to protect the health and safety of our staff, the public and the community.

The Church of Scientology has taken the measures to ensure the health and safety of our staff, parishioners and all local residents on our property.

Whilst the Church property is not public land, we are taking extra measures to maintain access for our neighbours and the community to enjoy the nearby National Park and walking tracks.

We are committed to creating a safe and peaceful environment for the community and Church members.