Israel was prepared to "significantly widen" its ground offensive against militants in the Gaza Strip, Prime Minister Benjamin Netanyahu said Friday.
He said the military was targeting the Hamas tunnel network, which it could not do "only from the air", BBC reported.
Thousands of troops moved into parts of Gaza Thursday night, backed by tanks and artillery fire.
Hamas, the Palestinian group that controls Gaza, has said Israel would "pay a high price" for the invasion.
The decision to send in troops came after 10 days of intensive rocket fire and airstrikes between the two sides.
"My instructions are to prepare for the possibility of significantly widening the ground operation, and the military is preparing accordingly," Netanyahu said.
At least 24 Palestinians and one Israeli soldier have been killed since the ground offensive began Thursday.
