Senior Israeli officials said on Thursday that an Israeli ground offensive into northern Gaza Strip was an act of defense against Palestinian rocket firing.

"Our presence there doesn't mean that we intend to remain in the Gaza Strip. We simply want to prevent firing at our towns," Infrastructure Minister Benjamin Ben-Eliezer told Army Radio.

David Baker, an official of the Prime Minister's Office, also defended the operation in the strip as an act with the aim of removing Palestinian rocket threat.

Meanwhile, army spokesman Jacob Dallal said that the operation was a limited incursion in a bid to ensure the release of an abducted Israeli soldier and stop rocket fire into Israel.

The Israeli army expanded its ground operation into northern Gaza Strip early Thursday by sending 15 tanks into the former settlements of Nissanit, Dugit and Elei Sinai.

As ground forces edged forward, Israeli artillery and airstrikes also struck Palestinian militant bases and groups in northern Gaza Strip.

Three Palestinians, including a Hamas activist, were killed and eight others wounded in an airstrike early Thursday.

After Qassam rocket for the first time hit the southern coastal city of Ashkelon Tuesday evening, Israeli political-security cabinet approved on Wednesday to step up operations in Gaza.

"We won't sink in the Gaza swamp, but will enter any necessary area to carry out our missions," Defense Minister Amir Peretz said on Wednesday.

Source: Xinhua