The three Arab-American men met with State Department officials Friday and complained that U.S. consular officers in Israel did little to protect them from the Israelis.
"The stories they told were very compelling and we take their concerns very seriously," a State Department official said Monday.
"We do have an abiding concern for the treatment of Americans," said State Department spokesman James Foley. "Our embassy has an obligation to act on behalf of American citizens who have been detained."
Two of the men, Yousif Marei of Chicago and Anwar Mohamed of Miami, were released without being charged after weeks in detention -- 36 days in Marei's case, 40 in Mohamed's.
The third man, engineer Beshar Saidi of Inkster, Michigan, said he signed a confession after 24 days of physical and psychological abuse.
On that basis, he was sentenced to five years in prison as an agent for a pro-Syrian Lebanese party that has attacked Israeli troops in south Lebanon, he said. Israel released and deported him 18 months later, in June.
All three told of poor conditions and rough treatment at Israeli interrogation centers. Mohamed, who owns a restaurant in Miami, said he lost 40 pounds in 40 days.
"I was handcuffed, chained, and my head was covered with a filthy bag and stretched into a contorted position for days at a time," Mohamed said in an affidavit.
A spokesman for the Israeli Embassy said Israeli authorities had reason to be suspicious of all three men, including the two released without charges.
He said long periods of detention without charges were needed to combat political violence.
Partners for Peace, a non-governmental organization promoting peace between Arabs and Israelis, took up their case and is lobbying for better consular service in Israel.
The group said Monday it was writing to Secretary of State Madeleine Albright to demand the immediate release of all U.S. citizens detained in Israel on what it called "so-called security suspicions or charges."
Albright will likely mediate in the dispute between Israel and the Palestinians over Palestinians detained in connection with politically motivated security offenses.
Partners for Peace said it is asking for a change in procedures so that consular officers automatically ask detainees if they want to officially protest.
U.S. consular authorities in Israel made a protest only in one of the three cases on the grounds that the other two Arab Americans did not specifically request one.
The State Department official said the three men provided signed affidavits Friday describing their experiences.
"What we are going to do is send these reports to or embassy and they are going to take them up with relevant authorities," Foley added.
Partners for Peace said the State Department's legal staff would advise the three on how to file a suit against Israel for monetary losses they allegedly suffered through detention and for compensation for their alleged pain and suffering.