The Palestinian Authority security forces have foiled an attempt by Hamas to assassinate senior PA leaders in the Gaza Strip, including PA Chairman Mahmoud Abbas and Fatah legislator Muhammad Dahlan, Palestinian security sources said Monday. The sources said that over the past few days the security forces discovered a number of underground tunnels in the northern Gaza Strip that were dug along major roads used by PA and Fatah leaders. Some of the tunnels were also discovered beneath the homes of top Fatah officials in the same area, the sources said. Abdel Hakim Awad, a senior Fatah official in the Gaza Strip, said tons of explosives were discovered in the tunnels, some of which were traced back to the interior of Hamas-controlled mosques.