A poster with a death threat on it directed at pro-Hong Kong protesters was protected by security guards for several days after being posted in the main foyer of a Sydney university.

Key points: One of the drawings read "Take back your Hong Kong independence speech if you don't want to die"

One of the drawings read "Take back your Hong Kong independence speech if you don't want to die" A pair of security guards remain near the University of Technology Sydney's poster wall

A pair of security guards remain near the University of Technology Sydney's poster wall The unrest in Hong Kong has sparked widespread protests in Australia

A pair of cartoons written in Chinese were found on a "Lennon Wall" near the University of Technology Sydney's (UTS) main entrance and were removed only after the ABC brought them to the attention of campus security.

One cartoon on the UTS wall showed a man holding another man over a cliff with the caption: "Take back your Hong Kong independence speech if you don't want to die".

Lennon Walls were popularised by pro-democracy activists during the Hong Kong Umbrella Movement in 2014 and are often the site of thousands of colourful post-it notes and posters calling for peace and unity.

Another shows a figure getting slapped and read "this slap is for the CPC Committee".

The Central Committee is a political body comprising of China's top leaders, including President Xi Jinping.

Part of the Lennon Wall at UTS last week. ( ABC News: Cameron Gooley )

The offensive materials were brought to the ABC's attention by a source inside UTS who wished to remain anonymous.

"My concern is that a small number of students are getting themselves so wound up with their nationalism that may be crossing the line and doing things which are illegal in Australia," they said.

"Some may not be aware of what they are doing, maybe some are aware but don't care."

The university earlier this month installed security guards after it created a dedicated space for the Lennon Wall — officially re-branding a "poster wall" — when materials belonging to pro-democracy and pro-One China activists around campus were found vandalised.

The university said it has so far been impressed with the "respectful behaviour" but had removed several inappropriate materials.

"A small number of posts not complying with the published rules have been removed, such as those over the size limits, or found to include offensive or hateful speech," a UTS spokesperson said.

Tensions flare as overseas unrest escalates

Pro-Beijing protest organisers claimed their posts on some Lennon walls had been torn down across university campuses, which they regarded as a deprivation of their freedom of speech.

On Saturday, Sydney had its first major pro-Beijing protests under the theme "Stop Riots in Hong Kong".

Protesters with Chinese flags gathered at Sydney Town Hall. ( ABC News: Sarah Hawke )

Jack Liang, who has been living in Australia for 20 years and is originally from Guangzhou in China, was one of the organisers of Saturday's demonstration.

"My normal life has been affected by the pro-Hong Kong protests in Hong Kong and Australia," he said.

"I felt deeply offended and discriminated because of the recent pro-Hong Kong protests."

He said the term "Chinas", a term widely viewed as a discriminatory language against people who come from mainland China, was being increasingly used in Australia.

Mr Liang claimed hackers had taken control of his website which he was using to collect and organise personal information about pro-One China protesters.

He said he did not believe that information, which included phone numbers and email addresses, was compromised but for several days he was unable to access the site's control panel ahead of the rally.

Thousands of pro-Hong Kong demonstrators have turned up at rallies across Sydney. ( ABC News: Kevin Nguyen )

Paranoia and feelings of "discrimination" have intensified in Australia as the political unrest in Hong Kong continued to escalate, particularly at university campuses.

Speaking Cantonese or Mandarin or using simplified Chinese has also become a point of contention on both sides.

One pro-Hong Kong organiser was upset and refused to be interviewed when she was approached by the ABC with a text message in simplified Chinese.