An expert on North Korea believes missing Perth man Alek Sigley may have been silenced amid heightened tensions in the country in the lead-up to US President Donald Trump's planned visit to the demilitarised zone in coming days.

Key points: Scott Morrison says he's concerned about a Perth man missing in North Korea

Scott Morrison says he's concerned about a Perth man missing in North Korea Alek Sigley's family and friends haven't had contact with the 29 year old for days

Alek Sigley's family and friends haven't had contact with the 29 year old for days The Prime Minister says limited information is emerging into the disappearance

Australian National University North Korea expert Leonid Petrov, a friend of Mr Sigley, said his disappearance and silence on social media channels and in response to messages from family and friends was very uncharacteristic.

"But in the context of what is going on in the Korean Peninsula today — President Trump on Sunday will go to the demilitarised zone and I believe tensions and security measures are heightened both in South and North Korea," Dr Petrov said.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 7 minutes 57 seconds 7 m Security ahead of Trump DMZ visit could be behind Sigley disappearance: analyst ( Girish Sawlani )

A family spokesperson confirmed Mr Sigley's social media accounts had been shuttered since his disappearance by his family to limit unnecessary speculation and commentary by the public on those channels.

Dr Petrov said Mr Sigley's regular blogging on North Korea, where he is studying at Kim Il-sung University and also runs a tour business for foreign visitors, could have been viewed as a security risk.

"Normally North Korea is a closed book," he said. "Information is protected, journalists are not permitted or very carefully scrutinised.

"So an international student studying at the university for more than a year and constantly bringing information about the reclusive country could have been seen as a potential distraction factor on the eve of a potential third summit between President Trump and North Korean leader Kim Jong-un."

Australian Alek Sigley married his Japanese-born wife Yuka Morinaga last year in Pyongyang. ( Facebook: Alek Sigley )

Prime Minister expresses concern

There is growing political concern for the welfare of Mr Sigley with the Prime Minister saying no new information has emerged into his disappearance since it was reported earlier this week by friends.

Scott Morrison said other world leaders had raised the plight of the Perth man, who has not made contact with his family for days, since the Australian delegation arrived in Japan for G20 meetings.

Scott Morrison says the Australian Government is trying to locate Alek Sigley, who's gone missing in North Korea.

"It is troubling to me and I'm sure his family as well," Mr Morrison told the ABC.

"The expressions of support and assistance that have come from other nations I have met with here has been very welcome.

"We will continue to focus sharply on that and seek to clarify what exactly has occurred and then take steps from there."

Doubts over danger posed to Australian

Dr Petrov said he did not think Mr Sigley was in immediate danger, due to the protection usually offered to foreign nationals in North Korea.

"International visitors and students are usually safe in North Korea because they are permitted to study there, they are trusted," he said.

Dr Leonid Petrov, a friend of Mr Sigley, doubted he was in danger. ( ABC News )

"But [he] is not controlled and not censored by the North Korean Government — we know it is a police state.

"[So he] may be considered by the North Korean regime as uncensored and potentially harmful."

Dr Petrov said it could well be that Mr Sigley re-emerged once the G20 was over and Mr Trump left the Korean peninsula.

"I don't think there is any danger to his wellbeing," he said.

"Perhaps he is being deliberately cut off from means of communication. It is a normal practice."

Diplomatic channels limited

Australia's diplomatic presence is limited in North Korea, but officials have been making urgent inquiries through Swedish diplomats.

Mr Sigley speaks fluent Korean and began studying for a master's degree in Korean literature at Kim Il-sung University in Pyongyang last year.

He married his Japanese wife Yuka Morinaga in a ceremony in Pyongyang last year.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 1 minute 9 seconds 1 m 9 s Alek Sigley married his Japanese wife in a ceremony in Pyongyang in 2018

He is believed to be the only Australian living in North Korea and sources have told the ABC that friends of Mr Sigley reported him missing earlier this week.

Australian spoke of safety in North Korea

In 2017 Mr Sigley told ABC Radio Perth he felt safe in North Korea.

"It's very safe," he said.

"I know lots of people who live there … expatriates, students, businesspeople and they all say it's very safe, they're not afraid to walk around at night and things like that.

"I've taken quite a few tour groups there and never really had any problems."

Mr Sigley does not appear to have touched his social media accounts in days. ( Facebook: Alek Sigley )

Asked whether he thought escalating tensions between the US and North Korea would affect tourism, Mr Sigley said he understood why people were apprehensive, but said it was "a cycle which happens almost every year … it's nothing really."

"There's also been a bit of an element of media hysteria and sensationalism as well, because some of these stories that are coming out are actually unsubstantiated," he said.

In a 2016 interview with ABC News Radio, Mr Sigley was asked whether he was concerned about what he could or could not say in North Korea.

President Donald Trump, meeting with Prime Minister Scott Morrison ahead of the G20, plans to visit the Korean peninsula this week. ( AP: Susan Walsh )

"When I go there I'm always so prudent not to cross the line and I think it's quite clear where the line is drawn," he said.

The Department of Foreign Affairs and Trade (DFAT) yesterday said it was "urgently seeking clarification" about his disappearance.

A spokeswoman for the Sigley family yesterday said it had not been confirmed if Mr Sigley had been detained, but said his social media silence was "unusual".