Israeli war planes have struck two media buildings in Gaza City, injuring at least eight journalists, including one who lost his leg, medical officials say.

Separately, Israeli air strikes continued in other parts of Gaza, including the north, where two children were killed in raids on homes.

As the strikes continued, the Israeli army said there had been no rockets fired into the Jewish state since 9pm (local time) on Saturday night, although around 7.30am there were reports of alert sirens in the south of the country.

And Hamas Prime Minister Ismail Haniya's office said he had spoken by phone with Egyptian President Mohammed Morsi to discuss the ongoing violence.

The first Israeli strike on a media building came around 2am on Sunday.

"At least six journalists were wounded, with minor and moderate injuries, when Israeli warplanes hit the al-Quds TV office in the Showa and Housari building in the Rimal neighbourhood of Gaza City," health ministry spokesman Ashraf al-Qudra said.

Witnesses reported extensive damage to the building, and said journalists had evacuated after an initial strike, which was followed by at least two more on the site.

The injured were taken to Gaza City's Shifa hospital. One journalist lost his leg in the attack, Qudra said.

A second hit on a different, nearby media building came around 7am.

"We have two journalists injured in the Shuruq building, which houses al-Aqsa TV, where there has been an air strike," Qudra said. Al-Aqsa TV is another Hamas-affiliated television station.

Imad Efranji, director of the al-Quds TV office, slammed the incident that targeted the station's facilities as "a new crime against the media".

"It was the media battle that forced Israel to stop its killing of children and civilians last time," he said, referring to Israel's December 2008-January 2009 Operation Cast Lead.

Elsewhere in Gaza, Israeli war planes carried out two separate raids on houses in the northern part of the strip that killed two and injured 10 others, Qudra said.

"Two young citizens were killed and at least 10 others wounded in two separate raids on houses in Beit Lahiya and Beit Hanun," he said, putting the Gaza death toll since the violence started on Wednesday at 48.

And another strike targeted a police station in eastern Gaza, injuring eight, he said, without specifying if they were police.

In Gaza City, as the Israeli air force attacked from above, Israeli naval forces opened fire, launching more than a dozen shells towards the shore, an AFP correspondent reported.

In a statement, the Israeli military said its aircraft had "targeted dozens of underground rocket launchers" overnight, as well as a "communications antenna."

"A short while ago, Saraya, a Hamas primary training base and command centre was targeted," the statement said.

"A communications antenna used by Hamas to carry out terror activity against the state of Israel, was also targeted."

"Israeli Navy soldiers targeted terror sites on the northern Gaza shore line," the statement added.

Haniya's office issued a brief statement saying: "During a 20-minute phone call between prime minister Haniya and Egyptian President Mohammed Morsi, Morsi described the efforts he has made to stop the aggression on Gaza."

- AFP