The largest-ever oil development project won by South Korea will help the nation to secure at least one billion barrels of oil worth about 110 trillion won (97.9 billion dollars), Seoul's presidential office said in a statement.

The deals were signed in Abu Dhabi by heads of the two states' oil agencies in the presence of visiting South Korean President Lee Myung-Bak and his UAE counterpart Sheikh Khalifa bin Zayed Al-Nahayan.

The preliminary deals, to be fully signed by 2012, allow Seoul to exclusively develop three new oil fields with total reserves of 570 million barrels in Abu Dhabi, where production will begin as early as 2013.

South Korea will also be allowed to take part in exploration at Abu Dhabi's major oil fields, with more than 1 billion barrels in reserve once current production contracts with other nations expire starting from 2014.

"South Korea today has received another big gift from UAE and Abu Dhabi... Today will be remembered as a special day," Lee said in a statement during a three-day state visit to the UAE.

Lee's last trip was made in December 2009 when Seoul won a 20.4-billion-dollar bid to build four nuclear reactors in the UAE -- the biggest single contract the Asian nation has ever won abroad.

South Korea is the world's fifth-largest crude oil importer and the UAE is its second-largest supplier after top oil exporter Saudi Arabia.

Seoul said the latest deal will help South Korea to secure 15 percent of its oil and gas consumption from energy sources it owns overseas, up from the current 10 percent, making the country less vulnerable to price swings for imports.

On Sunday, the two countries also reached a separate agreement to forge closer cooperation in industries including semiconductors, media and finance.