New York  - UN Secretary General Ban Ki-moon condemned Thursday the firing of rockets from southern Lebanon towards Israel and has ordered an investigation by the UN peacekeeping force in the region.

UN investigators found evidence that two rockets were fired Tuesday towards Israel and a rocket launching site was found near the village of Rachaya el-Foukhar and fragments of two rockets were discovered in the area of Ain Arab inside Lebanese territory.

Israel fired two retaliatory artillery rounds, which landed near Rachaya el-Foukhar and southeast of Khiam.

Ban said he was concerned about the escalation of hostilities across the so-called blue line serving as a frontier between Israel and Lebanon. Southern Lebanon remains a stronghold for Iran-backed Hezbollah militants, which fought Israel in the summer of 2006. (dpa)