Police in Tel Aviv said a bomb placed on the commuter bus detonated while the vehicle was near Israel's sprawling defense ministry complex, the Kiriya.

Condemnation also came from UN Secretary General Ban Ki-moon as he shuttled from talks with Palestinian leaders in Ramallah in the West Bank on to Cairo where diplomatic efforts continued to clinch a ceasefire between Israel and Gaza militants.

Referring to the bus bombing, Ban said "there are no circumstances that justify the targeting of civilians."

He also called for an "immediate cessation of indiscriminate rocket attacks by Palestinian militants targeting Israeli population centers."

US Secretary of State Hillary Clinton, meanwhile, held a second meeting with Israeli Prime Minister Benjamin Netanyahu, after earlier assuring him of "rock solid" US support for Israel's security.

Clinton, who had also visited Ramallah, traveled on to Cairo late on Wednesday, for talks with Egyptian President Mohamed Morsi, who has a lead role in mediation efforts.

Six killed in Gaza

A spokesman for the health ministry in Gaza, which since 2007 has been ruled by the radical Palestinian movement Hamas, said among the at least six people killed during Israel's latest airstrikes on Gaza City was a toddler.

A building next door used by the French news agency AFP was also hit. The agency said its journalists were absent at the time.

The death toll since Israel launched its offensive by targeting and killing a Hamas military chief last eight days ago stands at 147 Palestinians and five Israelis killed.

Israel's military said on Wednesday that over that period Gaza militants had fired nearly 1,400 rockets into Israel. Israel in turn had carried out more than 1,500 military strikes.

An Israeli political source quoted by Reuters said hopes of a ceasefire were being held up by a Hamas demand that Israel lift its blockade of Gaza completely. Earlier, Netanyahu had told Clinton that Israel wanted a "long-term" solution.

Iran providing technology

Iranian media on Wednesday quoted the chief of Iran's Revolutionary Guards General Mohammad Ali Jafari as saying that Iran had "provided" technology to enable Gaza militants to produce missiles "quickly."

"We are proud to defend the people of Palestine and Hamas … and that our assistance to them has been both financial and military," said Ali Larijani, Iran's parliament speaker, according to the ICANA.ir parliament website.

After recent missile firings toward Tel Aviv, Israel had accused Iran of supplying its Fajr 5 rocket, which has a range of up to 75 kilometers (46 miles).

The United Nations refugee agency in the Gaza Strip, UNRWA, said on Wednesday the humanitarian situation for its 1.7-million population was worsening.

"The situation for civilians is bad," said UNRWA spokesman Christopher Gunnes. "People only go out when absolutely necessary."

ipj/dr (dpa, Reuters, AFP)