World leaders gathered for a second summit on nuclear security are poised to approve more specific plans and new pledges of action to prevent nuclear terrorism and ensure atomic safety, diplomats said Tuesday.

Top leaders from 53 nations and four international organizations, including U.S. President Barack Obama and Chinese President Hu Jintao, on Monday kicked off a two-day meeting dedicated to making the world a safer place without the threat of nuclear terrorism.

The second Nuclear Security Summit in Seoul is a follow-up to the first summit hosted by Obama in Washington in 2010, when leaders focused on strengthening the security of fissile material worldwide and securing against nuclear terrorism.

In Seoul, world leaders are set to assess accomplishments of commitments made in Washington and lay out more concrete actions to curb the threat of nuclear terrorism and illicit trafficking.

On the first day of the summit, South Korean President Lee Myung-bak hosted a working dinner with world leaders and cited "substantial progress" over the past two years.

Presiding over a plenary session on the second day of the summit, Lee called for international cooperation and collaboration to bolster global defenses against nuclear terrorism.

"It is my sincere wish that during this Seoul summit we can build on that progress and yield more advanced and practical commitments and agreements," Lee told world leaders.

"In particular, significant advances must be made in eliminating and minimizing the use of nuclear materials including highly enriched uranium and plutonium, and enhancing international cooperation, which is crucial in detecting, tracking and responding to illicit trafficking of nuclear material," Lee said.

Lee also noted, "There is no place that can be free from nuclear terrorism. We all share the same fate. I believe that it is our joint responsibility to work towards making a community of peace."

Over the past two years, more than 10 nations, including Australia and Argentina, got rid of some 400 kilograms of highly enriched uranium, which are enough nuclear material to make approximately 16 nuclear weapons.

The U.S. and Russia, the world's two largest nuclear superpowers, also eliminated seven tons and 48 tons of highly enriched uranium each, according to the summit's organizing committee.

Negotiators, or "sherpas" from the 53 nations held their final meeting in Seoul on Friday and fixed the agenda for the Seoul summit and discussed the text of a so-called "Seoul Communique"

that will be announced at the end of the summit.

"Sherpas have already agreed the Seoul Communique will pledge to minimize the civilian use of highly-enriched uranium and plutonium," said a senior Seoul diplomat said on the condition of anonymity, adding the text will include "practical visions and concrete actions" on ways to promote global cooperation and enhance measures for nuclear materials and facilities from being exploited by terrorists.

"Also, at least 10 more nations will separately pledge to eliminate their stocks of highly-enriched uranium and plutonium," the diplomat said.(Yonhap News)