Israeli air strikes killed 22 people in Gaza on Monday, raising the overall death toll to 100 on the sixth day of a relentless bombing campaign.

In the latest raids, one person was killed when Israeli warplanes hit the Shuruq tower media centre in Gaza City, which houses Palestinian and international media outlets, among them official Hamas broadcaster Al-Aqsa TV.

Islamic Jihad sources named him as Ramez Harb and said he was a senior commander in its armed wing, the Al-Quds Brigades.

European Union foreign ministers Monday called for an "immediate" halt to hostilities in Gaza and Israel. "An immediate cessation of hostilities is in everyone's interest, particularly at a time of instability in the region," the bloc's 27 ministers said in a statement. "All attacks must end immediately as they cause unjustifiable suffering of innocent civilians."

United Nations secretary general Ban Ki-moon also arrived in the Egyptian capital of Cairo to push for a Gaza ceasefire.

The United States needs to deploy a high-level envoy, like former President Bill Clinton, to help negotiate a peace deal between Israel and the Palestinians, senator John McCain said.

Washington needed to show it was serious about wanting peace in West Asia and sending someone as senior as Clinton would help, he said.