Chief negotiators for South Korea and the European Union reached a tentative free trade agreement Tuesday after nearly two years of talks, but left key issues of a «political nature» for their trade ministers to resolve next week in London. Officials for the two sides told reporters that they had reached a «provisional» accord in almost all areas during two days of talks, but that they remained far apart in certain contentious areas, including duty drawback and rules of origin, according to a report of Associated Press. EU chief negotiator Ignacio Garcia Bercero indicated that serious work remained to be done, cautioning that «success is not guaranteed» and that «nothing is agreed until everything is agreed.» Lee Hye-min, Garcia Bercero's South Korean counterpart, echoed the latter sentiment, adding that he is «neither optimistic nor pessimistic» regarding the eventual outcome of the negotiations. South Korea and the 27-member EU have been working to reach a deal to slash tariffs and other barriers to commerce for nearly two years. They touted their two days of talks this week as the final round at the level of chief negotiator. The EU and South Korea are already major trade partners. Bilateral exchange reached $98.4 billion in 2008. The EU is South Korea's second-largest trading partner after China and is its largest foreign investor.