The armed wing of the radical Islamic Jihad on Thursday said it had fired an Iranian-built rocket at the Israeli city of Tel Aviv.
"The Quds Brigades hit the occupied city of Tel Rabea (Tel Aviv) with a Fajr 5 rocket causing a large explosion to shake the city," the group said in a brief statement, shortly after an AFP correspondent reported seeing a rocket land in the water south of the sprawling coastal city.
"What comes next will be greater," the statement added.
In a separate statement, posted on the group's website, spokesman Abu Ahmed pledged that Israel would experience "further surprises so long as the aggression against the Palestinian people continues."
"The enemy began the battle but the resistance will determine how the battle will end," he said.
The rocket was the farthest that a Gaza rocket had ever hit inside Israel, and came as the Israeli air force pressed a major bombing campaign across the Hamas-run territory.
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"A rocket crashed into the water just outside of Jaffa," an AFP correspondent said, as Israeli police confirmed that warning sirens had gone off across Tel Aviv.
In a televised news conference shortly after the sirens went off, the military's official spokesman said that no rocket had "hit the ground."
"Despite the sirens, nothing hit the ground. The direction (of the rocket) was apparently towards the southern part of Gush Dan," Yoav Mordechai said in a televised press conference, referring to the region in and around greater Tel Aviv.
Images shown on Israel's Channel 2 television showed people lying on the ground outside the defence ministry in central Tel Aviv, their hands over their heads as the sirens wailed.
Israeli news networks said it was the first time rockets had been fired at the city since the 1991 Gulf War, when it was hit by Iraqi Scud missiles.
Tel Aviv-Jaffa lies some 60 kilometres (36 miles) north of the Gaza Strip. Fajr 5 rockets have a range of up to 75 kilometres (46 miles).