Israel locked down the West Bank and Gaza Strip today ahead of its national election, after conducting a large-scale military incursion into Gaza and hearing warnings that Palestinians may try to disrupt the voting with violence.

The military said it was completely sealing the West Bank and Gaza Strip for three days to prevent Palestinian militants from sabotaging Tuesday's election. Stringent travel bans have been enforced since the outbreak of fighting in September 2000, and the new restrictions, taking effect today, mean all Palestinians are confined to their towns and unable to enter Israel.

There were general warnings of attacks by Palestinians over the next 48 hours, but no more than usual, a police spokesman said.

Also today, Israeli soldiers shot dead a 7-year-old Palestinian boy who was playing in the Rafah refugee camp in the Gaza Strip, Palestinian medics and relatives said. The Israeli army said it knew of no such incident. A 50-year-old Palestinian man was killed outside his home in the same area by an Israeli tank shell, Palestinian security officials said. The Israeli military said soldiers opened fire on suspicious figures moving in a forbidden area near the Gaza-Egypt border.

The Gaza City raid, which killed at least 12 Palestinians, was the deepest Israeli incursion into the Palestinian city of 300,000 in more than two years of fighting. The raid came in response to the firing of crude, short-range Qassam rockets at the Israeli town of Sderot in the southern Negev Desert, near Gaza, on Friday.

The Israeli military said its forces "raided dozens of buildings used as weapon-producing workshops" and destroyed equipment. Soldiers also blew up two houses they said belonged to militants. Five more Qassam rockets were fired at Israel today, causing no damage or injuries.