Australian Prime Minister Julia Gillard, during an official visit to Beijing this week, will urge China to pressure North Korea to abandon nuclear weapons production.

Gillard, who will lead an Australian delegation, wants China to tighten enforcement of U.N. sanctions against Pyongyang, including the sale of Chinese equipment and technology that could allow development of a nuclear program.

Australian Foreign Minister Bob Carr will seek similar assurances during his planned discussions with Chinese State Councilor Yang Jiechi, a report by The Age newspaper said.

The official Australian five-day visit starts Friday and Gillard will meet Chinese President Xi Jinping and Premier Li Keqiang. Discussions are to focus on trade, security and climate change.

The visit also comes as North Korea threatens to restart a reactor at the Yongbyon nuclear complex mothballed in 2007. A statement by North Korea said the reactor could produce weapons-grade plutonium that would boost the country's nuclear forces "in quality and quantity," a report by the BBC said.

North Korean leader Kim Jong Un said Pyongyang's nuclear weapons were a "treasure."

He also has declared the country in "a state of war" with the South.

Tensions have been rising steadily this year between North and South Korea -- still technically at war after a 1953 cease-fire ended a three-year war but split the Korean Peninsula politically. No peace treaty has been signed.

North Korea recently reacted angrily to U.S.-South Korean military drills and the latest round of U.N. and U.S. sanctions after Pyongyang's Feb. 12 underground nuclear test.

U.S. F-22 stealth jet fighters have been poised in South Korea for war games this week. The U.S. military command in South Korea said it flew the fighter aircraft, known as the Raptor, to Osan Air Base, 40 miles south of Seoul, from Japan's Kadena Air Base near Okinawa, to showcase its most potent weaponry to North Korea.

A spokesman for Australia's Foreign Ministry said U.N. sanctions would be more effective if there were tighter implementation on ships and planes going to North Korea, including from China -- North Korea's main ally.

"That's something we'll be talking about when we're in China," he said.

"It is not suggested China is breaching the sanctions. China voted for them in the Security Council but China is the principal conduit for supplies to North Korea," The Age quoted the spokesman as saying.

"We're going to emphasize the importance of taking action on North Korea but we appreciate you have to approach that in a manner that recognizes their relationship rather than just bursting in and telling them our view of the world."

New U.N. Security Council sanctions introduced last month include tougher financial restrictions and bans on luxury goods such as yachts, high-end cars, jewelry and perfumes.

Carr also recently said he is considering more sanctions on top of the extended U.N. measures that would hit the banking and financial services in Australia used by North Korea's elite.