Israel will pay a "high price" for launching a ground invasion of the Gaza Strip, the Palestinian Hamas movement said on Thursday night.

"The start of the Israeli ground attack on Gaza is a dangerous step, the consequences of which have not been calculated," said Hamas spokesman Fawzi Barhum in a statement.

"Israel will pay a high price and Hamas is ready for the confrontation."

The comments came after Israel announced it had launched a ground operation.

"Following 10 days of Hamas attacks by land, air and sea, and after repeated rejections of offers to de-escalate the situation, the Israel Defence Forces (army) has initiated a ground operation within the Gaza Strip," the army said in a statement.

Israel launched Operation Protective Edge on July 8 to stamp out rocket attacks from Gaza, but confined it to air attacks until late Thursday.

So far at least 240 Palestinians and one Israeli have been killed.

-AFP