Two rockets fired from Lebanon struck northern Israel before dawn Tuesday, the military said, causing no injuries but expanding the violence that has erupted on Israel's borders ahead of U.S. President George W. Bush's visit to the region.

One of the rockets landed on a road, and the other on the porch of a home in the town of Shlomi.

Israeli Defense Minister Ehud Barak called the attack "grave," and said Israel was investigating, Israeli media reported. Prime Minister Ehud Olmert's office had no response.

It was the second rocket attack on Israel from Lebanon since Israel's summer 2006 war with Lebanese Hezbollah guerrillas. In June, two rockets fired by a previously unknown group, the Jihadi Badr Brigades — Lebanon Branch, fell in Israel, causing minor damage but no injuries.

Israeli military officials said it appeared the same group was responsible for Tuesday's attack, although there was no claim of responsibility.

A senior military officer in Beirut told The Associated Press that the Israeli report was "baseless and completely fabricated." He spoke on condition of anonymity because he was not authorized to discuss the incident with the media.

Yasmina Bouziane, a spokeswoman for U.N. peacekeepers in Lebanon, said the force had a team on the ground looking into the report. "In the meantime, we can't confirm or deny" the Israeli claims, she said.

A resident of Shlomi, Simona Salamon, said a rocket hit her porch in the middle of the night.

"It was such a big noise and my ears were ringing," Salamon told Army Radio. "It made a hole in the wall."

During the 2006 war, Lebanese Hezbollah guerrillas bombarded northern Israel with nearly 4,000 rockets. Forty Israeli civilians were killed in the war, along with 119 Israeli soldiers. More than 1,000 Lebanese — most of them civilians— were killed in Israeli bombardments.

Separately, a Lebanese shepherd detained Monday by Israeli troops in the disputed Chebaa Farms area was released Tuesday to U.N. peacekeepers in Lebanon, Lebanese and Israeli military officials said. Lebanese security officials said the shepherd had been herding his goats when he wandered inside the area, a small slice of territory where the borders of Lebanon, Syria and Israel meet.

The rocket fire from Lebanon comes on the heels of Israeli clashes with Palestinians in the Gaza Strip and West Bank.

Israeli troops carried out an incursion in central Gaza after militants fired a rocket Thursday that struck deep into southern Israel. They also conducted a four-day raid in the West Bank town of Nablus, uncovering a weapons laboratory and other munitions, and arresting 20 wanted men.

The tensions on Israel's northern and southern fronts threatened to cast a pall over Bush's three-day visit to Israel and the West Bank, which begins Wednesday.