Israeli jets carried out fresh air raids on tunnels under the Gaza-Egypt border, reportedly sending hundreds of people fleeing their homes in panic.
Local residents and Hamas security officials said three air attacks took place before dawn on Wednesday, but no casualties have yet been reported.
The raids came just hours before the newly appointed US Middle East peace envoy was due to arrive in Israel.
Israel has confirmed that it carried out the raids.
It says the attacks on the Rafah tunnels are aimed at stopping alleged "weapons smuggling" into the Gaza Strip by Hamas fighters.
The tunnels are also used to smuggle food, fuel and consumer goods from Egypt and are considered a life-line for thousands of ordinary Gazans.
Fragile ceasefires
The latest attack came despite fragile ceasefires declared by Israel and Hamas last week, ending a 22-day Israeli military campaign on Gaza in which 1,300 people were killed.
Israeli jets had targeted scores of cross-border tunnels during the recent war.
PHOTO CAPTION
Smoke rises after an Israeli air strike in Rafah in the southern Gaza Strip January 17, 2009.
Al-Jazeera