Palestinian President Mahmoud Abbas, saying Hamas is partly to blame for the latest bout of violence in Gaza, has sought to enlist Egypt's help to halt the rapidly deteriorating situation in Gaza and the West Bank. "The situation is deteriorating very gravely and if it does not come under control, it will be complicated and a third party, such as the Quartet, should intervene to stop the escalation of the events," chief Palestinian negotiator Saeb Erikat said on Wednesday after two hours of talks between Abbas and Egyptian President Hosni Mubarak. The Quartet refers to the EU, UN, US and Russia, who back the road map peace plan for the Israelis and Palestinians. Erikat said the two leaders discussed "the continued [Israeli] settlement activities, the ongoing building of the separation wall and the grave deterioration in the situation in Gaza". Israel on Wednesday widened its five-day campaign against Palestinian fighters, firing artillery shells into the Gaza Strip for the first time and shutting down 15 West Bank offices suspected of distributing money to families of bombers from the Hamas and Islamic Jihad groups. Israeli aircraft also fired missiles at several Gaza targets, knocking out power in Gaza City for most of the night. In the West Bank, Israel rounded up 24 suspected fighters, bringing the number of people arrested since the weekend to more than 400. Palestinian policemen also exchanged fire with armed men who approached the Gaza Strip's border with Israel on Wednesday, the first domestic clash since Israeli soldiers completed a pullout from the territory this month. Witnesses said the armed men wounded two policemen and took at least one more hostage near Karni border crossing. The identity of the armed men was not immediately clear, nor their reason for approaching the border.