TEL AVIV (AFP) - Israeli Prime Minister Ehud Olmert on Friday raised the spectre of a full-scale military operation in the Hamas-run Gaza Strip despite Egyptian attempts to mediate a truce. "According to the information as it is now, the pendulum is much closer to tough military action," Olmert told journalists on arrival in Israel following a three-day trip to the United States. The Israeli Premier also suggested that the door to a negotiated truce was not completely closed. He said his government was still considering whether to avoid getting "into a violent and hard conflict with the organisations in Gaza" or to launch "operations that would be much more aggressive and hard." On Friday, a military engineering unit operating armoured bulldozers on the Gaza side of the border was embroiled in a firefight with Hamas gunmen, the military said. A member of Ezzedine al-Qassam Brigades, the armed wing of Hamas, was killed and an Israeli soldier was wounded in the exchange of fire. Earlier on Friday at least 10 Palestinians were wounded in an Israeli air raid on a Hamas police post in the north of the Gaza Strip, Palestinian medics said. Elsewhere, six Qassam rockets and four mortar rounds fired from Gaza slammed into southern Israel, an Israeli army spokesman claimed. Hamas confirmed four Qassam rockets had been fired. It was not immediately clear if they caused damage or injuries. At least 491 people, all Palestinians, have been killed since Israeli-Palestinian peace talks resumed in November, according to an AFP count. The Israeli military alleged on Friday that Palestinians fired more than 2,300 rockets and mortar bombs at Israel in the past six months. On Friday, hundreds of people gathered on the Gazan side of the closed Rafah border crossing with Egypt for a demonstration called by Hamas to protest against the Israeli blockade. Hamas wants Egypt to open the border crossing - the only gateway to Gaza not under Israeli control. Around 500 Egyptian police were called in as reinforcements to ensure there was no repeat January's border breach, when Gaza militants blew open large sections of the border fence, sending hundreds of thousands of Palestinians pouring into Egypt to stock up on vital supplies. It was resealed a few days later. Egypt has been acting as mediator in the truce talks because Israel refuses to negotiate directly with Hamas, which it considers a terrorist organisation.