Israeli warplanes have carried out raids in Gaza and troops have entered the strip with bulldozer tanks, sources have said.
The jets attacked areas on Thursday in the Zaiton area, southeast of Gaza city, and Biet Hanon, to the north, Al Jazeera has learned. Earlier, Israeli media said two rockets had been fired from the strip into Isreal, which landed in an empty areas.
There were no injuries reported in Gaza from the air raids.
The AFP news agency meanwhile quoted witnesses as saying that Israeli troops backed by armour entered the strip on Thursday, drawing mortar fire from Palestinian fighters, without immediately reporting any casualties.
The incursion was east of the southern city of Khan Yunis.
"Six military bulldozers accompanied by several tanks entered about 200 metres from the border into farmland, as helicopters and spy planes circled above near the village of Khuzaa," one witness told AFP.
"Resistance fighters fired several mortar rounds at the Israeli forces and explosions were heard in the area," the witness added.
An Israeli army spokeswoman was unable to confirm the incursion, but said "a mortar round hit Israel near the Gaza border fence. There were no casualties or damage."
Palestinian group Islamic Jihad said its fighters responded to the incursion with mortar fire. Al Jazeera could not confirm the details of the incursion.