The tanks, which entered around 400 metres (yards) into the Palestinian territory, were accompanied by a bulldozer, but it was unclear whether a demolition was planned.

Israel has often demolished structures and cleared land along Gaza's border with the Jewish state, citing security concerns.

An Israeli military spokesman told AFP he could neither confirm nor deny any incursion.

Israel and Hamas are formally committed to a truce agreed after Israel's devastating 22-day Operation Cast Lead, which ended in January 2009.

But in recent months, militants have fired dozens of rockets into southern Israel, prompting retaliatory airstrikes by the Israeli military.