Penny Wong has blasted WeChat campaigns targeting Labor with fake news, as a new claim emerges warning refugees will soon outnumber Chinese Australians.

On Tuesday Wong, Labor’s foreign affairs spokeswoman, demanded Scott Morrison “rule out any Liberal party involvement in the malicious false content” and linked the messages to potential foreign interference in Australian democracy.

In one set of messages, seen by Guardian Australia, Liberal supporter Jason Zong cites Labor’s policy to increase the humanitarian intake to 32,000, claiming “in 10 years that will be 320,000 and that’s not including their relatives and four wives who can all immigrate”.

“After 10 years this group of refugees will surpass Australia’s entire Chinese immigrant population, and there will be more in the coming years and the taxpayers will have to pay for it,” he said.

Jason Zong at a Liberal National party event with former prime minister John Howard. Photograph: WeChat

On Sunday a WeChat message from Jennifer (Jing) Li emerged pushing a doctored Bill Shorten tweet stating “immigration of people from the Middle East is the future Australia needs”.

The tweet has also appeared on Gab, the far-right social media network resembling Twitter, although several users there noted it was fake and used the wrong handle for Bill Shorten.

Labor has written to TenCent, the Chinese multinational which created WeChat, raising concerns.

At a press conference in Melbourne, Wong said there are “deeply concerning reports about fake news and malicious content being spread on WeChat”.

“Our message to the prime minister is this: this is not what we do in Australia.

“We have robust political debates. We don’t have major political parties engaging in fake news on this media platform or any other media platform.

“It is incumbent upon Scott Morrison to rule out any Liberal party involvement in the malicious false content that is circulating on WeChat.”

Wong noted the 45th parliament had passed foreign interference laws to prevent interference in Australian elections and ensure “our democracy remains sovereign” and called on Morrison to “do the right thing”.

A Liberal party spokesman responded: “These are not ads distributed by the Liberal party. All Liberal party advertising carries an official authorisation.”

The Coalition campaign spokesman, Simon Birmingham, told ABC TV “yes”, he can rule out the involvement of the Liberal party in the messages.

“I’m confident if there are things that are being said that are incorrect, they are not coming from our campaign, it is a social media platform … and we don’t control the comments of the millions of different users of WeChat,” he said.

Labor and the Coalition are both keen to court the votes of Chinese Australians, particularly in the Victorian seat of Chisholm where Liberal Gladys Liu and Labor’s Jennifer Yang are contesting the seat on a margin of 2.9%.

In 2016 Liu masterminded a Chinese social media campaign that helped elect Liberal candidate Julia Banks, and has claimed Chinese Australians are concerned future generations will be “destroyed” by “ridiculous rubbish” such as “concepts of same-sex, transgender, intergender, crossgender”.

Liu has also denied she favoured Chinese migrants in comments from 2016 that suggested “not as good migrants” from other countries were less hard-working.

Zong is a Liberal supporter, pictured at numerous party events including with the Liberal candidate for Kogarah, Scott Yung, and former prime minister John Howard.

Zong correctly stated if Labor wins the 18 May election it would give $500m to the UN’s refugee council – omitting the fact the spending is over five years – and claims it will increase Australia’s foreign aid by 25%, although the quantum of Labor’s proposed spending money is still unknown.

Referring to the refugee intake, Zong said: “The first year will require about $1bn and every year that will increase, and eventually it might reach $10bn dollars.”