Palestinians say Israeli troops shot and killed two Palestinian men as Israel moved tanks and troops into the southern Gaza Strip Wednesday.
Residents identified the two as militants from the armed wing of the governing Palestinian faction Hamas.
They say a large number of Israeli soldiers entered the town of Rafah, taking up positions outside the main border terminal with Egypt. The witnesses say Israeli bulldozers tore up land near the terminal.
An Israeli spokesman confirmed the deaths and said troops were searching for tunnels used to smuggle weapons into Gaza from Egypt.
News reports from Israel say one of the dead men was involved in the June kidnapping of an Israeli soldier Corporal Gilad Shalit, but this has not been confirmed.
Elsewhere, Palestinian witnesses said Israeli troops shot and killed two Palestinian men overnight in the northern Gaza Strip.
Israeli politicians said on Tuesday that an expanded Gaza offensive was in the works.
The Rafah border crossing is Gaza's only direct access to the outside world. Israel has kept it mostly closed since June, when Palestinian militants kidnapped the Israeli soldier.
Israel launched a large-scale offensive in the Gaza Strip at the end of June, aimed at stopping Palestinian rocket attacks and freeing the soldier. Israeli ground troops withdrew from the Strip in early September.
