DALLAS — A group that was once the nation’s largest Muslim charity went on trial on terrorism-support charges yesterday, with federal prosecutors saying the group hoped to destroy Israel and the defense claiming its leaders sought advice on staying true to their humanitarian mission.

The trial of the Holy Land Foundation for Relief and Development is expected to last several months and caps an FBI investigation that lasted more than a decade. The organization and five of its top officials are charged with aiding terrorists, conspiracy, and money laundering.

Prosecutor James Jacks said in his opening statement that the foundation was created to raise money for the Palestinian Arab group Hamas. The charity’s leaders lied about their purpose “because to tell the truth is to reveal what they were all about — the destruction of the state of Israel and replacing it with a Palestinian Islamic state,” he said.

Some of the money went to support the families of suicide bombers, according to authorities.

Defense attorneys say Holy Land supported humanitarian efforts in Palestinian Arab neighborhoods and did not knowingly aid Hamas. “Holy Land had nothing to do with politics. Its focus was on children in need,” Nancy Hollander, lawyer for Holy Land chief executive Shukri Abu Baker, said in her opening statement.

Defense lawyers said Holy Land approached American officials, including prosecutor Jacks, asking how to stay on the right side of the law while working in the Middle East.

“They were never told to stop working with anyone,” Ms. Hollander said. Defense lawyers also said the government’s U.S. Agency for International Development worked with some of the same Middle Eastern charity groups that Holy Land did, and that none of the groups Holy Land worked with appeared on terrorism watch lists. Contact with Hamas has been illegal since 1995, when President Clinton designated it a terrorist group.