Seoul is ready to open a two-day nuclear summit in Seoul later Monday, with leaders of 57 nations and international organizations gathered for the country's biggest international gathering to date.

Leaders from 53 nations, including 39 heads of state, and four international organizations have convened for the second Nuclear Security Summit. The leaders will also hold approximately 250 bilateral summit meetings on its sidelines, according to the event's Preparatory Secretariat.

South Korean President Lee Myung-bak will have met with 27 global leaders, including U.S. President Barack Obama, China's Hu Jintao, Russia's Dmitry Medvedev and U.N. Secretary-General Ban Ki-moon.

First launched by Obama in Washington two years ago, the biennial summit is aimed at working out more specific actions to prevent loose nuclear materials from falling into the hands of terrorists.

About 40 private planes have landed at three main airports in the capital area, including Incheon International Airport. Other participants traveled on commercial flights, officials at the secretariat said.

Over 3,700 reporters and journalists from around the world have registered at the International Media Center, located close to the conference hall of the Convention and Exhibition Center, the summit's main venue, as the high-tech media center opened on Sunday, they added. The center offers an on-site translation service in 18 languages, including English, Japanese, Chinese, Russian, German, French and Arabic.

A total of some 40,000 officials from the country's foreign ministry, volunteers and security personnel are tasked with providing services in the fields of transportation, accommodation, public relations and tourism during the summit, organizers said.

Many details of the tightened security measures are shrouded in secrecy, but work has taken shape at airports, hotels, conference venues and other sites, they said. Some 1,000 vehicles have been mobilized for security purposes and more than 360 limousines were prepared for the summit attendees.

The South Korean government has asked Seoul citizens to participate in the voluntary traffic campaign in which only vehicles with even-numbered plates are allowed on the road on Monday and those with odd numbers are allowed on Tuesday, the organizers said. To alleviate possible transportation problems, more buses and subway trains have been put into operation and over 2,800 traffic police officers have been dispatched.