Israeli soldiers have fired rubber bullets at protesters who approached the controversial security barrier Israel is building around Palestinian areas.
Washington has expressed concern at the Israeli barrier
A spokesman for the pro-Palestinian International Solidarity Movement said at least seven foreign activists and two Palestinians were hit by bullets but were not seriously hurt.
The Israeli army said troops had used "non-lethal means of crowd-dispersal" against a group of protesters trying to vandalise the fence.
US Secretary of State Colin Powell warned on Friday that the West Bank barrier could undermine the peace plan, known as the roadmap.
"When the fence is no longer just on (Israeli) land... it
starts to infringe and take over Palestinian land," Mr Powell told Israeli newspaper Maariv.
"And you see it going in ways that will make it very
difficult to get to the next phases of the road map."
Witnesses said more than 300 Palestinian and foreign activists were involved in Friday's protests, which took place near the West Bank town of Tulkarm.
Israel says the 600 kilometre-long (370 mile) barrier is to keep out suicide bombers, but Palestinians say it cuts into their territory.
On Thursday, Israel announced it would build 22 new homes in the Gaza Strip, despite being required under the roadmap to freeze settlement expansion.
US state department spokesman Richard Boucher said talks were under way on the issue after news of the tender drew Palestinian condemnation.
"A freeze is a freeze," he said.
ROADMAP MAIN POINTS
Phase 1 (to May 2003): End to Palestinian violence; Palestinian political reform; Israeli withdrawal and freeze on settlement expansion; Palestinian elections
Phase 2: (June-Dec 2003) Creation of an independent Palestinian state; international conference and international monitoring of compliance with roadmap
Phase 3 (2004-2005): Second international conference; permanent status agreement and end of conflict; agreement on final borders, Jerusalem, refugees and settlements; Arab states to agree to peace deals with Israel
But he added that there were "very involved aspects" to the issue, such as "so-called natural growth".
The peace process received another setback this week when the Israelis and Palestinians failed to agree on the latest stage of Israel's military withdrawal from Palestinian territories.
Israel has pulled out of the West Bank town of Bethlehem and parts of the Gaza Strip, but under the roadmap, the plan is to withdraw gradually from other Palestinian areas.
In talks in Jerusalem on Wednesday night, Palestinian security chief Mohammed Dahlan had sought Israel's withdrawal from Ramallah, where Mr Arafat has been marooned for more than a year by Israeli forces.
But Israeli Defence Minister Shaul Mofaz would only agree to withdraw from Jericho and Qalqilya.
Jericho has been largely bypassed by nearly three years of violence and its handover would be seen as a formality.
Qalqilya, however, is at the edge of the West Bank, just a few kilometres from the Israeli city of Kfar Saba.
Hundreds of demonstrators protested in the town on Thursday against a controversial security fence being built by Israel.
The talks breakdown clouded the first high-level talks since the Israeli and Palestinian prime ministers paid separate visits to Washington over the past seven days to discuss the US-backed roadmap peace plan.