The Christian Peacemaker Teams (CPT) said in a statement that "the actions of the US and UK governments" were to blame for the abduction of the four activists.
The organisation is an umbrella group for pacifist church activism. It issued a statement on Tuesday confirming that the four men associated with their organisation were kidnapped in Iraq by an armed group calling itself the Swords of Righteousness Brigade.
Aljazeera aired a video showing four peace activists who were captured in Iraq by a previously unknown group, but it could not verify any of the information on the tape.
The tape, which aired on Tuesday, showed four men and a British passport belonging to Norman Kember. The four workers are an American, a Briton and two Canadians.
CPT said it had had a team in Iraq since October 2002, working with US and Iraqi detainees and training others in nonviolent intervention and human rights documentation.
Iraq's influential Association of Muslim Scholars (AMS) has appealed to the abductors to release the four. The AMS said in a statement received by Aljazeera.net that those workers have a respectable record for helping the poor and disadvantaged.
The AMS has helped secure the release of many foreigners abducted in Iraq since the US-led invasion in 2003.
"We demand that these aid workers be released immediately"
Mufti Ikrema Sabri,
top Palestinian Muslim scholar
Abductors of the four workers accuse them of being spies for the "occupation forces".
Fighters in Iraq have claimed that they set up a fair trial for the people they abduct.
CPT officials in Hebron in the West Bank have vehemently denied the charges, stressing that the four opposed the war on Iraq and Bush's policies.
Rich Meyer, a CPT leader, told a news conference in Hebron on Wednesday: "We are very worried about our friends. We fear that whoever is holding them has made a mistake. They are four men who came to Iraq to work for peace. They oppose the occupation. They are not spies."
Palestinians led by their top Muslim cleric appealed to Iraqi fighters on Wednesday to release the four, saying three of them had spent time in the West Bank aiding the Palestinians.
While in the West Bank, American Tom Fox and the two Canadians demonstrated against the construction of Israel's separation barrier in the West Bank, helped Palestinian children to get through Israeli army checkpoints and pitched in with the olive harvest, Palestinians across the West Bank said Wednesday.
Mufti Ikrema Sabri, the Palestinians' leading Muslim clergyman, said:
"We demand that these aid workers be released immediately. We tell them that these aid workers have stood beside Palestinian people, and it's our duty now to stand beside them."
Palestinian civil society activists
want the four Westerners freed
Sabri said Islam opposes taking civilians hostage and said such kidnappings are inhumane.
Palestinians in several towns said they had worked with the three activists and asked Sabri to issue the appeal.
Hundreds of international activists have aided the Palestinians in largely peaceful demonstrations during more than five years of fighting with Israel.
freedom for occupied peoples, like the Palestinian and Iraqi peoples."
Shawkat Samha, mayor of Jayyus village in the West Bank, said: "They subjected themselves to grave dangers when they stood in front of Israeli bulldozers.
"'We knew them as people who were against occupation and supported
He said that he had met Fox and recognised him in the video shown on Aljazeera.
Fared Tomallah, from the West Bank village of Salfit, said he cried when he recognised Harmeet Sooden, a Canadian, on television.
CPT activist Rich Meyer says one
captive was to return to Hebron
"I saw him many times suffering through tear gas with the Palestinians when demonstrating against the wall," Tomallah said, referring to the separation barrier.
"We appeal to Iraqi insurgents to release him, and we assure them that these people have nothing to do with the occupation."
The local branch of Christian Peacemaking Teams in Hebron
said that one of the captives, James Loney from Toronto, Canada
, had helped Palestinian children get through Israeli army roadblocks in the divided city.
Loney was slated to return to Hebron next week to continue his work, said Rich Meyer, an activist with the group.
"The kidnapping prevents him from coming here to work," Meyer said.
Aljazeera.net's Khalid Amayreh in the West Bank and Ahmed Janabi contributed to this report.