Palestinian officials say more than 1,000 people have been killed during Israel's 19-day offensive against Hamas in the Gaza Strip.

The head of the United Nations children's agency, Ann Venemen said Wednesday that 300 children were among the dead.  She said 1,500 others have been wounded and said the casualties were "tragic" and "unacceptable."

Israel has tightly controlled access to the Palestinian territory, so the numbers can not be independently verified.  But U.N. officials have said previous estimates have been generally credible.  Thirteen Israelis have died in the conflict.

Also on Wednesday, the head of the International Red Cross called the situation in Gaza "shocking." Jakob Kellengerger visited the densely-populated territory Tuesday, as well as the Israeli town of Sderot, which has been repeatedly hit by Hamas rockets.  He called on both sides to differentiate between military targets and civilians.

Meanwhile, Israel bombed more Hamas targets in Gaza on Wednesday, including smuggling tunnels.  Hamas launched at least a dozen rockets into southern Israel.

Israeli launched the offensive in Gaza on December 27 to halt years of Palestinian rocket attacks.

Separately, police say three rockets were fired from Lebanon into northern Israel on Wednesday, landing outside the town of Kiryat Shmona.  There were no reports of casualties, and no claim of responsibility.  The Lebanese government denounced the rocket fire. 

It was the second such attack in less than a week.

Officials say Israel fired shells into Lebanon in response.

Also Wednesday, Israeli police said militants fired a phosphorus shell from Gaza into Israel. 

Human Rights Watch has accused Israel of illegally using the shells in populated areas.  The phosphorus mortars create a smokescreen but also cause burns.

Israel said Wednesday that an Iranian ship carrying two thousand tons of aid to Gaza was turned back Tuesday because it violated a general maritime blockade of the territory, not because of the ships point of origin.  

Iran, which does not recognize Israel, has condemned its offensive in Gaza. 

Some information for this report was provided by AFP, AP and Reuters.