Twenty Palestinians were killed Wednesday, including a Reuters cameraman, in Israel Defense Forces operations in the Gaza Strip, making Wednesday one of the bloodiest days in recent times in Gaza. Most of the clashes came in the afternoon in the center of the Strip, not far from the place where three Israeli soldiers were killed in a Hamas ambush earlier in the day.

The fierce day of fighting started at around midnight on Tuesday, when a patrol from the Givati infantry brigade, accompanied by armored and artillery forces, entered the Sajawiya neighborhood on the east side of Gaza City. The soldiers exchanged fire with armed Palestinians, mostly from Hamas. One Givati soldier was moderately wounded in the thigh by a sniper. The soldiers killed four Hamas gunmen. According to military sources, the Palestinians even fired from the minaret of a mosque, and the IDF returned fire at the mosque and later blew up explosive devices found inside the mosque. The mosque suffered heavy damage, and the resulting pictures caused furious responses in the Muslim world.

A Palestinian farmer, Hani Al-Zuarub, was killed at 3:00 P.M near Beit Lahiya in the northern Gaza Strip, when a missile hit the car he was in. Another man was wounded. Three others were injured by shots fired at a school in the town.

Twelve Palestinians were killed, including five children under the age of 16, Wednesday afternoon when IDF helicopters fired missiles at houses in the Juhad Al-Dik area.

Three more Palestinians were killed near the Wadi Gaza Bridge, including Reuters cameraman Fadel Shana, 23. He died when the car he was riding in was hit by a missile. Two other journalists were wounded. Pictures showed the car had the letters "TV" on it, as is usual for vehicles used by journalists in the region.

Footage from Shana's camera showed an Israeli tank firing a shell in his direction from several hundred metres away.

IDF sources expressed regret Wednesday over Shana's death. "Nevertheless, it must be remembered that there are battles against terrorist cells in the area on a daily basis. This fighting endangers the press and others not involved who are nearby." The IDF has not yet said whether it will conduct an official investigation into the death.

Four Hamas militants were killed in an exchange of fire with IDF troops east of the Sajawiya refugee camp. Five more Palestinians were wounded in the area, three of them critically.

Hamas official Sami Abu Zuhri said his group's armed wing was authorized to "strike the Zionist enemy everywhere".

The government of Palestinian President Mahmoud Abbas censured the Israeli attacks but said the peace talks would stay on track. Prime Minister Salam Fayyad told reporters that the negotiations were meant to stop Israel's "incursions, siege and daily killing".

Meanwhile, United Nations Secretary General Ban Ki-moon said he was "gravely concerned" by the escalation of violence in southern Israel and the Gaza Strip, and urged all sides to "exercise restraint."

A statement from a UN spokesman said Ban "condemns the reported civilian casualties among Palestinians, including children, during Israeli military operations."

He also "reiterates his condemnation of rocket fire against Israeli civilian targets" by Palestinian militants in the Gaza Strip.

Fuel limitsThe Nahal Oz fuel depot remained closed; Israel shut it April 9 after militants killed two Israeli civilians at the facility. The Ministry of Defense had said it would reopen the depot but the latest attacks put that into doubt.

Kanan Abaid, deputy chairman of the Palestinian Energy Authority in the Gaza Strip, said before pumping resumed that the power plant only had enough fuel to operate until Saturday.

The EU official said the goal was to provide "as much [fuel] as can be possibly pumped today" because the army had yet to tell the Europeans whether they would be allowed to make further deliveries to the plant on Friday.

The plant supplies power mainly to residents of Gaza City and the vicinity, home to 800,000 people.

A strike by Gaza petrol station owners has been preventing distribution of limited Israeli supplies of gasoline and diesel to the general public.

Israeli officials accuse Hamas of preventing distribution of petrol and diesel in order to create a crisis to pressure Israel to ease a blockade it tightened after the Islamists took over. In a development likely to stoke further anger in Israel, Hamas said former U.S. President Jimmy Carter, who planned to travel later in the day to Egypt, would meet in Cairo with two of its Gaza-based leaders, Mahmoud al-Zahar and Saeed Seyam.

"Mr Carter asked for the meeting. He wanted to hear the Hamas vision regarding the situation, and we are interested in clarifying our position and emphasising the rights of our people," Hamas official Ayman Taha said.

Carter's delegation in Israel declined to comment.

Zahar, speaking in Gaza before leaving for Egypt, said Carter had been able "to break all the restrictions preventing him from meeting Hamas leaders".

Israeli leaders have shunned Carter over his contacts with Hamas, which has rejected Western demands to recognise Israel, renounce violence and accept existing Israeli-Palestinian interim peace deals.

Carter, who began a Middle East visit on Sunday, said in Arab East Jerusalem it would be counterproductive to exclude Hamas completely from "conversations or consultations".