Jerusalem  - A human rights groups accused Israel Saturday of apparently using white phosphorus in violation of international law.

Human Rights Watch (HRW) said Israel seemingly employed the substance as an obscuring tool, which is legal, but said that given Gaza's high population density, and the chance that civilians would be hurt, Israel should discontinue the use.

"We completely believe that the use of white phosphorus in densely populated areas is a violation of international humanitarian law," Marc Garlasco, a military analyst with the group, told Deutsche Presse-Agentur dpa by phone from the Israel-Gaza border.

"White phosphorus has a significant, incidental, incendiary effect that can severely burn people and set structures, fields and other civilian objects in the vicinity on fire," HRW explained in a statement.

"White phosphorous can burn down houses and cause horrific burns when it touches the skin," Garlasco said.

The Israeli military would only issue a standard statement, saying that it does not use illegal weapons.

"The weapon itself is not illegal, if used as a smokescreen, in open areas, that's fine," Garlasco noted, adding "but today we saw them use it over the Jabalia refugee camp, a densely populated area."

He said the military was not "not taking proper precautions to protect the civilian population."

A military statement said Israel operated in accordance with international law.

"Understandably, operational considerations prevent the IDF from going into detail about the weaponry it possesses or uses," the statement read, using the acronym for the Israeli forces. (dpa)