In the deadliest such confrontation in years of anniversary clashes usually confined to the West Bank and Gaza, Israeli forces opened fire in three separate border locations to prevent crowds of demonstrators from crossing frontier lines.

The new challenge to Israel came from the borders of Lebanon, Syria, Jordan and Gaza - all home to hundreds of thousands of Palestinians who fled or were driven out in 1948.

Combined with a public relations disaster last year over the killing of pro-Palestinian activists in a Gaza aid flotilla and a determined Palestinian diplomatic drive to win UN recognition of statehood in September this year, the bloody border protests raised the stakes further for Israel.

Israel's leaders condemned the incidents as provocations inspired by Iran, to exploit Palestinian nationalist feeling fueled by the popular revolts of the "Arab Spring," and to draw attention from major internal unrest in Syria, Iran's ally.

Israeli Prime Minister Benjamin Netanyahu said he hoped the confrontations would not escalate.

Palestinian President Mahmoud Abbas, whose Fatah movement holds sway in the Israeli occupied West Bank and is ready to negotiate peace with Israel, said in a televised address that those killed were martyrs to the Palestinian cause.