Israeli troops entered the southern Gaza Strip, starting a broad ground operation on early Wednesday following the abduction of an Israeli soldier by Palestinian militants on Sunday, witnesses said.

The Israeli army has confirmed the start of the offensive, code-named "Summer Rain", adding that the military operation was aimed to secure the return of the kidnapped soldier.

It is the first major ground offensive by the Israeli army since Israel withdrew troops and soldiers from the entire Gaza Strip last summer after 38 years of occupation.

Witnesses said that Israeli tanks were moving into the Rafah town, adding that loud blasts were heard.

There was no report of any casualties so far.

Just moments ago, Palestinian security forces said that the Israeli army demanded Palestinian security forces to withdraw from the key Rafah crossing on the southern Gaza border.

Around midnight Tuesday, Israeli airstrikes destroyed three bridges linking the north and the south of Gaza in a bid to prevent Palestinian militants from moving the abducted Israeli soldier.

The only power plant in the Gaza Strip was also hit by missiles, which led to a blackout in most areas of the coastal strip.

The 19-year-old Israeli Corporal Gilad Shalit was snatched by Palestinian militants who mounted a deadly attack on an Israeli army post near the Gaza border on Sunday.

Israeli Prime Minister Ehud Olmert has turned down demands by the Palestinian militants to set free Palestinian women and minors jailed by Israel in exchange for information on the abducted soldier.

Two other Israeli soldiers were killed and four wounded in the predawn Sunday attack. Two Palestinian militants were also shot dead in the gunbattle with Israeli forces.

Israel has vowed retaliation for the cross-border assault.

Editor: Yan