Declaring war on the talks promoted by US President Barack Obama as he prepared to host a White House banquet with Israeli and Palestinian leaders, the Hamas militants said Tuesday's killings were just the first phase.

Palestinian leaders committed to the peace process joined Israel and the United States in condemning the attack and said direct Palestinian-Israeli negotiations, suspended for 20 months but due to resume this week, would not be derailed.

Hamas, which controls the Gaza Strip, opposes the peace talks and is not taking part. It says Palestinian President Mahmoud Abbas, who controls the West Bank, is a "traitor" for talking to the Israelis about a peace deal.

Jewish settlers in the West Bank said the killings displayed the folly of trying to make peace with the Palestinians.

Mr. Obama is staking precious political capital on the drive to resolve a conflict now over six decades old, and the Washington talks were engineered by his Middle East envoy George Mitchell.

Before holding talks with the US President and the Israeli PM, the Palestinian leader condemned "any operation that targets civilians, Palestinians or Israelis."

The four Israeli settlers, two men and two women, one of them pregnant, were shot dead after nightfall on the busy Highway 60 close to the West Bank city of Hebron. The road is used by both Palestinians and Israeli settlers.