The United States, joined by Arab mediators, has sought to conclude an agreement between Israel and Hamas to halt the 14-month-old conflict in the Gaza Strip, where medics said Israeli strikes killed at least 20 Palestinians yesterday, according to . A Palestinian official close to the negotiations said that mediators had narrowed gaps on most of the agreement’s clauses. He said Israel had introduced conditions which Hamas rejected but would not elaborate. Medics said an Israeli airstrike killed at least 10 people in a house in the northern town of Beit Lahiya while six were killed in separate airstrikes in Gaza City, Nuseirat camp in central areas, and Rafah near the border with Egypt. In Beit Hanoun in the northern Gaza Strip, medics said four people were killed in an airstrike on a house. There was no immediate comment from the Israeli military spokesman. Later yesterday, medics told that an Israeli strike on a house in Jabalia killed at least 10 people.