SEOUL, Korea, Republic Of -- Late North Korean leader Kim Jong Il repeatedly pushed for summit talks with South Korea before his 2011 death but the plans failed because Pyongyang demanded $10 billion and large-scale shipments of food and fertilizer, a former South Korean president says in a memoir to be published next week.

Parts of the memoir by ex-President Lee Myung-bak, provided to reporters in advance, reveal that senior intelligence officials from the two Koreas made secret visits to each other's countries to explore summit possibilities in 2010, when two deadly attacks blamed on Pyongyang killed 50 South Koreans. Lee says a North Korea envoy who visited Seoul that year was later publicly executed after returning to the North.

The memoir comes as both countries float the idea of a possible summit between Kim's son and current leader, Kim Jong Un, and Lee's successor, President Park Geun-hye. It would be the third summit meeting since the two Koreas were divided 70 years ago, although chances seem low as the countries bicker over the terms for talks.

The first summit in 2000 prompted an era of co-operation between the rivals, but also became a source of criticism in South Korea. Conservatives said Seoul's then "sunshine policy" of providing generous economic aid to Pyongyang with few strings attached supported the North's nuclear and missile development.

Lee, a conservative who ended a decade of liberal rule in South Korea in 2008, halted such aid and refused to implement rapprochement projects signed in the second summit in 2007. His actions earned him public loathing in North Korea, where state media called him a "rat" and a "traitor."

Lee writes in his memoir that the "sunshine policy" was tarnished because North Korea diverted aid to nuclear and missile development and continued to stage provocations against South Korea.

Lee, who severed as president from 2008 to 2013, saw tension spike sharply after his inauguration. A soldier killed a South Korean tourist in North Korea in 2008, and North Korea staged long-range rocket and nuclear tests in 2009. But Lee says that in 2009 North Korea began proposing a summit meeting between him and Kim Jong Il. The proposal came when senior North Korean officials visited Seoul to pay respects to late President Kim Dae-jung, who participated in the first summit with Kim Jong Il in Pyongyang and won a Nobel Peace Prize for his efforts to reconcile with the North.

Those efforts were damaged when a close associate of Kim Dae-jung was convicted in 2006 of pressuring the Hyundai conglomerate into sending $450 million to North Korea shortly before the 2000 summit.

Lee says one of the North Korean officials who visited Seoul, Kim Ki Nam, told him that Kim Jong Il had said it wouldn't be difficult for the leaders of the two Koreas to meet again if agreements signed during the 2000 and 2007 summits were carried out. Five days after the meeting, Lee says North Korea called for a "considerable amount" of rice, fertilizer and other aid shipments in return for a summit.

On the sidelines of a regional conference in Beijing in October 2009, Lee says Chinese Premier Wen Jiabao told him that Kim Jong Il had sent a message that he wanted a summit. Lee says he was willing, but didn't want to pay for the meeting and wanted the North's nuclear program on the agenda.

Later in 2009, officials of the Koreas met secretly in Singapore, and North Korea insisted on economic aid in exchange for a summit. Lee says the North later said it wanted 400,000 tons of rice, 300,000 tons of fertilizer, 100,000 tons of corn, asphalt worth $100 million, and $10 billion for the establishment of a development bank in North Korea.

Prospects for summit talks were further hurt after a South Korea-led international investigation blamed North Korea for torpedoing a South Korean warship and killing 46 sailors in March 2010. The North launched an artillery strike on a South Korean island that killed four people in November of that year. North Korea has denied involvement in the ship sinking.

North Korea's state media didn't immediately comment on the contents of Lee's memoir.