Palestinian security forces uncovered a Hamas bomb-making laboratory in Nablus a week ago, where 33 kilograms of mercury and other materials used to make bombs were found, Palestinian sources said Thursday.
The bombs were to be used against Israel but also against Palestinian Authority targets, the sources said.
The hazardous materials were found in a building Palestinian intelligence believed was serving as a Hamas arms cache. Mercury is often used to complete the electrical circuit in bombs - basically an "on" switch for detonation.
In recent weeks the Palestinian security forces carried out a broad security operation in Nablus against Hamas networks. Several dozen Hamas activists were arrested, and most were released after they agreed to turn in their weapons and avoid any activities against Israel or the PA.
http://www.haaretz.com/hasen/spages/941702.html