Israel kills 4 Hamas fighters

Gaza: Israeli soldiers shot dead four Hamas fighters in the Gaza Strip on Wednesday during an incursion in the occupied Palestinian territory, drawing promises of revenge in a further setback to a fragile ceasefire.

Aid groups said they feared the flare-up could derail Israeli plans to reopen border crossings with the Gaza Strip on Thursday to allow in humanitarian supplies for the first time in over a week.

The UN Relief and Works Agency (UNRWA), which provides food and other essentials to Palestinians in Gaza, said Israel's blockade was targeting the world body directly.

"This has become a blockade against the United Nations itself," UNRWA spokesman Christopher Gunness said, citing a long list of supplies, including food, that Israel has yet to allow into the coastal territory.

An Israeli army spokeswoman said soldiers entered the Hamas-controlled Gaza Strip after opening fire at gunmen preparing to plant explosives along the border. The Islamist group said the men belonged to its armed wing.

Hamas spokesman Ayman Taha said: "This [Israeli] escalation is dangerous and we will not stand still. There will be a painful response against the Zionist enemy."

Palestinian groups in the territory launched eight mortar bombs into Israel during and after the clash, the army said. There were no casualties or damage.