Both Hamas and Islamic Jihad distanced themselves from the roadside explosion which devastated a diplomatic convoy in Beit Hanun on Wednesday morning.
An armed group calling itself the Popular Resistance Committees denied any responsibility for the deadly attack after AFP said it recieved a call from a member of the group saying it carried it out.Palestinian President, Yasir Arafat, condemned the attack as an "ugly crime", and said he had ordered an investigation.
The FBI also said it would send a team to the Gaza Strip to investigate the bombing, said US ambassador to Israel Daniel Kurtzer.
And chief Palestinian peace negotiator, Saib Uraikat, said no Palestinian group would commit such an attack.
“The US convoy included a group of US observers, not CIA members, who were observing events happening on the ground in the area, such as the implementation of the road map and the Israeli and Palestinian commitment towards it,” he said.
Yasir Arafat has condemned the
attack as an 'ugly crime'
“Such an incident will lead to disastrous consequences on the area, as Israel will have a justification to dissolve the observation teams there,” he added.
However, Israeli Foreign Minister Silvan Shalom accused the Palestinian Authority of covering for "terror organisations".
"The Palestinian Authority is not doing anything to break up the terror infrastructure and is continuing to cover for the extremist organisations," Shalom said in a statement after the blast.
A team of US investigators briefly inspected the site of the attack, Palestinian security sources and witnesses said.
Six investigators spent about 15 minutes at the site near the Erez border crossing into Israel, inspecting a crater left by the force of the explosion.
The investigators videographed the wreckage before they were briefly forced to stop when youths from the Jabalya refugee camp pelted them and their vehicles with stones.
Israeli helicopters hovered as the US investigators arrived, and tanks located about 500m from the scene fired sporadically at the ground and into the air to secure the area.
Soldiers also fired machineguns earlier after an armoured jeep was damaged by a landmine nearby. Three soldiers were lightly wounded in that attack.
Beit Hanun blast is the first attack of its kind in the Palestinian territories against a US target.
It came just hours after the United States vetoed a resolution at the UN Security Council which condemned Israel's construction of its Apartheid Wall across the West Bank.
In a separate incident, Israeli troops shot dead a Palestinian man near the northern West Bank town of Tulkaram on
Wednesday, said Palestinian security services.
Bilal Zaidane, 23, was killed in Ramin village, six
kilometres east of Tulkaram. There were no further details.