PHNOM PENH, Cambodia (AP) - South Korean president Lee Myung-bak will pay an official visit to Cambodia next week to promote ties and develop economic relations.  A statement issued Wednesday by Cambodia's Foreign Ministry said Lee will hold talks with Prime Minister Hun Sen during his Oct. 22-23 visit, and the two countries will sign agreements on extradition and the framework for loans from Seoul.  Foreign Ministry spokesman Koy Kuong said South Korea is the second-biggest investor in Cambodia after China, mainly in agriculture, real estate and construction.  The Yonhap news agency says South Korean investment in Cambodia increased to nearly $2.5 billion last year from $30 million in 1997. The report cited the president's office in Seoul.