The Israeli military said on Sunday it intensified operations in the southern Gaza city of Khan Younis, destroying dozens of Hamas targets in a blitz of air and artillery strikes.

The air force and artillery hit about 50 targets within six minutes, it said, in a bid to "intensify operational achievements in the area."

"During the strikes, the troops destroyed terrorist infrastructure and eliminated Hamas terrorists who were operating from civilian facilities in urban areas," it said.

Residents in the area said they were surprised by the swift advancement of Israeli tanks, which sparked fresh battles with Palestinian gunmen. In one housing project some families took to social media, saying they were unable to leave their homes with the tanks in the streets.

Palestinian militant group Islamic Jihad said it attacked two tanks with rockets and blew up a building where soldiers had entered.

Khan Younis has been a focus of Israel's military offensive in recent weeks.