The phosporus that the Israelis deny using is the the stuff you see on Newsnight, the rather spectacular white plumes.
Telegraph
11th January, 2009
White phosphorus is an incendiary material that causes severe burns when it comes in contact with human skin and its use in conflict zones is restricted inside civilian areas. Syria called on the UN to investigate the claim.
Human Rights Watch said its researchers witnessed the use of the materiel on Saturday and Sunday in Gaza City and Jabalia refugee camps, both built-up areas.
The Israeli military, which refuses to comment on the types of munitions it is using in the conflict, rejected the accusations. “There is no use of white phosphorus,” a spokeswoman said. “Everything we use is according to international law,” Marc Garlasco, senior military analyst at Human Rights Watch said: “Israel should not use it in Gaza’s densely populated areas.”