GAZA CITY, Gaza Strip - Former President Jimmy Carter criticized Israel's blockade during a trip to Gaza yesterday while encouraging the territory's Hamas rulers to accept international conditions for ending its boycott of the extremist Islamic group.

During his visit, Hamas security found what appeared to be explosives buried in a sand dune next to Carter's route. No one was hurt, and it was unclear whether the former president was being targeted.

Speaking at a graduation for students from U.N.-run schools in Gaza City, Carter criticized the Gaza blockade imposed by Israel and Egypt after Hamas took control, saying Gazans "are treated more like animals than human beings."

Carter's one-day Gaza visit came at the end of a swing through Lebanon, Syria, and Israel, during which he encouraged officials in all countries to move toward a negotiated end to the Middle East conflict.

Carter, who helped broker the historic peace treaty between Israel and Egypt, serves a unique role in peacemaking efforts in the region.

Although traveling as a private citizen and not a representative of the U.S. government, Carter said he would report to Obama administration officials after returning to the United States.

Carter has advocated talking to all parties in the conflict, even Hamas, which the United States, the European Union, and Israel consider a terrorist organization and do not deal with directly.

Carter said that one of his trip's main goals was to persuade Hamas to accept the West's conditions for engaging the group: renouncing violence, recognizing Israel, and accepting previous Israeli-Palestinian accords - all of which Hamas has refused to do.

At a news conference in Tel Aviv after leaving Gaza, Carter said he was waiting for Hamas to determine what it could agree to.

"When they make their decision on the exact language, they'll be back in touch with me, and I'll relay that commitment to the government officials in my country," Carter said.

While in Gaza, Carter met with civil leaders and toured areas damaged in Israel's three-week offensive against Hamas, which ended Jan. 18.

"I have to hold back tears when I see the deliberate destruction that has been wreaked against your people," he said. Noting that many Israeli weapons are built in and provided by the United States, he added: "I feel partially responsible for this, as must all Americans and all Israelis."

He also called for an end to the rocket attacks on Israel by Gaza militants.

"All this violence must stop in order for me and others to have a chance to help you find peace," he said.