Chinese President Hu Jintao and leaders from over 50 nations and international organizations met Tuesday in Seoul to explore ways to strengthen international cooperation in nuclear security.

At the Seoul Nuclear Security Summit, the leaders are expected to review the achievements made since the Washington summit in 2010.

They will discuss cooperative measures to combat the threats of nuclear terrorism, protect nuclear materials and related facilities, and prevent illicit trafficking of nuclear materials.

In his biweekly radio address last week, South Korean President Lee Myung-bak, host of the summit, said that currently, radioactive materials that can be utilized to make as many as 130,000 nuclear weapons are scattered around the globe.

"The objective of the Nuclear Security Summit is to prevent such nuclear materials from falling into the hands of terrorist groups," he said.

In addition, the leaders will also exchange views on strengthening nuclear safety, which drew renewed attention following the Fukushima nuclear disaster in Japan last year.

The Fukushima accident, triggered by a strong earthquake and tsunami on March 11 last year, raised global concern about nuclear safety.

The process of building new reactors around the globe has slowed down since the disaster.

China attaches great importance to the issue of nuclear security and firmly opposes nuclear proliferation and nuclear terrorism.

Chinese diplomats said that President Hu will make an important speech at the summit and elaborate on China's position, efforts made and important measures taken in the field of nuclear security.

"As a huge country for nuclear energy development, China has always attached great importance to nuclear security and actively participated in international cooperation in nuclear security," Chinese Assistant Foreign Minister Ma Zhaoxu told a press briefing last Tuesday.

Ma said China hopes the Seoul Nuclear Security Summit will further improve international consensus and promote international cooperation in nuclear security.

According to the International Atomic Energy Agency (IAEA), from 1993 to 2011, more than 2,100 incidents of nuclear and radioactive materials had been confirmed, of which about 400 incidents involved unauthorized possession, movement or attempts to illegally trade or use nuclear and radioactive materials.

Khammar Mrabit, director of the IAEA's Office of Nuclear Security, said more needs to be done to improve the security of nuclear and radioactive materials worldwide.

"Nuclear and other radioactive materials are still not properly secured. We have roughly around 200 incidents per year," he told a press briefing last week.

The Seoul summit is a follow-up of the first summit in Washington in April 2010. At the Washington summit, leaders from 47 states and three international organizations discussed plans to strengthen nuclear security by preventing the misuse of nuclear materials by non-state actors.

On the sidelines of the summit in Seoul Monday, the Chinese president met U.S. President Barack Obama, South Korean President Lee and South African President Jacob Zuma. They discussed bilateral ties and issues of common concern.

After the Seoul summit, Hu will travel to New Delhi, India, for a meeting of BRICS countries -- Brazil, Russia, India, China and South Africa. The Chinese leader will then visit Cambodia.

(Xinhua News Agency March 27, 2012)