The Israel Defense Forces (IDF) on Saturday evening began its ground operation in the Hamas-ruled Gaza Strip, an IDF spokesman told Xinhua.

The Cast Lead operation starting last Saturday is now entering its second stage, said the spokesman, adding that the purpose of the operation is to destroy "terror infrastructure of Hamas."

IDF troops have now entered Gaza, he said, adding that the operation will last as long as necessary.

"The objective is to destroy the Hamas terror infrastructure in the area of operations," IDF Major Avital Leibovitch, a military spokeswoman, was quoted by local daily Ha'aretz as saying, while confirming that ground incursions were under way.

"We are going to take some of the launch areas used by Hamas," she said.

The IDF spokesperson's office issued a statement, emphasizing that this stage of the operation will further the goals of the eight-day offensive as voiced by the IDF until now: to strike a direct and hard blow against Hamas while increasing the deterrent strength of the IDF, in order to bring about an improved and more stable security situation for residents of southern Israel over the long term.

Meanwhile, local daily The Jerusalem Post reported that a large amount of Armored Corps, Engineering Corps and Infantry troops entered Gaza, exchanging fire with Hamas gunmen.

The IDF warned that militants using civilians as human shields would bear full responsibility for their fate, said the report, adding that Israeli cabinet also approved the call-up of thousands of reservists, mostly from combat units, but also from the Home Front Command.