ISRAEL has been accused of firing fearsome - and possibly illegal - white phosphorus shells in Gaza as its forces cut the 40km-long coastal territory in two. White phosphorus, believed to have been used to cause a dense smokescreen as troops and tanks advanced, can cause horrific burns to anyone coming into contact with it. Its use as a military weapon is forbidden in civilian areas under the Geneva Treaty of 1980. Experts quoted in the British media said that if white phosphorus had been used in an area as heavily populated as Gaza, Israel might have committed a war crime. The Israeli military has denied using the controversial munitions, but acknowledged their use during its 2006 war against Hezbollah in Lebanon. British and United States forces also used it - drawing heavy criticism - during the 2003 invasion of Iraq. It is not illegal if used as a smokescreen. "Israel uses munitions that are allowed under international law," spokesman Ishai David was quoted as saying in the Daily Mail - but declined to elaborate on the type of shells used during the Gaza operation. In any case, by yesterday, the Israeli ground offensive - which came after eight days of air strikes since Dec 27 - had cut Gaza, controlled by the militant Hamas, in two. Israel had said ground operations were needed because rocket attacks by Hamas fighters on civilian areas in southern Israel had continued despite air strikes. Israeli Defence Minister Ehud Barak has insisted the offensive in Gaza would proceed, reported the BBC. Israel, which goes to the polls next month, launched 30 air strikes last night. Heavy clashes were reported east of Gaza City, the largest urban area. Moves to seek a ceasefire or a diplomatic resolution, led by France, have gathered pace as the death toll shot past 500. A Hamas delegation was expected in Egypt, which European Union foreign-policy chief Javier Solana had said could play a "fundamental" role in bringing about a ceasefire. However, Hamas was still talking tough: Top leader Mahmud Zahar yesterday vowed Hamas was heading to "victory".