An expert says Australia could be reached by a potential nuclear attack by North Korea.

The comments come as North Korea restarted a nuclear reactor this week, seen as its main source of weapons-grade plutonium, raising concern over its nuclear and ballistic missile programs.

Australian National University Korea expert Leonid Petrov, told news.com.au that the communist state would be able to produce enough weapon-grade plutonium to create a nuclear bomb each year.

• North Korea ready to use nuclear weapons ‘any time’
• North Korea unleashes submarines
• South, North Korea high-level talks fail to end crisis

But they would be more likely to target South Korea, Japan and the USA, who had more strategic importance or military operations.

That could still impact Australia, though, with Mr Petrov saying we “wouldn’t go unscathed” if a nuclear explosion occurred in another Asian country.

“We have citizens residing and working and travelling all over Asia,” he said.

“Australia is definitely going to be impacted by any significant escalations of tensions in Korea.

“If the conflict in Korea is triggered, and there is a full-on nuclear combat situation…we’re likely to be involved in the conflict.”

North Korea have previously threatened to “punish” Foreign Minister Julie Bishop after comments she made to US media about leader Kim Jong-un.

This week’s confirmation, by the head of the Korea Atomic Energy Institute, came hard on the heels of suggestions by the chief of the national space agency of a possible satellite rocket launch next month.

In an interview with the North’s official KCNA news agency on Tuesday, the director of the AEI said all facilities at the Yongbyon nuclear complex, including a five-megawatt reactor, had “started normal operations”.

North Korea mothballed the Yongbyon reactor in 2007 under a six-nation aid-for-disarmament accord, but began renovating it after its last nuclear test in 2013.

When fully operational, the reactor is capable of producing around six kilos of plutonium a year – enough for one nuclear bomb, experts say.

The AEI director said scientists had been “steadily improving” both the quality and quantity of the North’s nuclear deterrent and he issued a by-now standard warning to the US.

“If the US and other hostile forces persistently seek their reckless hostile policy … (North Korea) is fully ready to cope with them with nuclear weapons any time,” he said.