Attorney General Eric H. Holder Jr. struck back against criticism that the FBI has targeted Muslims in a series of undercover stings, telling a Muslim group Friday night that those who allege government entrapment "simply do not have their facts straight."

In one of his most pointed and personal responses to allegations that government anti-terrorism tactics are overly aggressive, Holder strongly defended the FBI agents he said are fighting a wave of terrorist plots. Without their efforts, he said in a speech in San Francisco, "government simply could not meet its most critical responsibility of protecting American lives."

Wading into the most controversial recent case, Holder backed the FBI's investigation of an Oregon man charged with trying to detonate a bomb at a Christmas tree lighting ceremony. FBI technicians had supplied the device, leading some Muslims and civil libertarians to question whether agents went too far by training the man for terrorism.

"I make no apologies for how the FBI agents handled their work," Holder said. He spoke in a hotel ballroom before an estimated 300 people invited by Muslim Advocates, a group that itself is suing the Justice Department to learn more about investigative guidelines for FBI agents.

"Those who characterize the FBI's activities in this case as 'entrapment' simply do not have their facts straight - or do not have a full understanding of the law," Holder said. The nation's chief law enforcement official praised FBI agents and Justice Department lawyers while reaching out to Muslims "who say they feel uneasy about their relationship with the United States government."

Holder's speech, the latest in a series of remarks on relations with Muslims, highlighted a national debate over government tactics that has built amid what authorities call the growing threat of homegrown terrorism. In recent weeks, undercover FBI operatives posing as Islamic radicals arrested the Oregon man and a Northern Virginia man accused of plotting to bomb Washington area Metro stations.

In the latest case, a Baltimore construction worker was charged Wednesday with plotting to blow up a military recruiting station in Maryland after the FBI learned of his radical leanings on Facebook. The FBI supplied him with a fake car bomb that he tried to detonate, federal officials said.

FBI-Muslim relations have periodically been difficult in the years since the Sept. 11, 2001, attacks as agents reached out to Muslims while also investigating them. Both sides agree that a partnership is critical to increasing mutual understanding and preventing attacks.

Tensions escalated last year after revelations that an FBI informant had infiltrated a mosque in California, seeking to build a terrorism case that later collapsed. Citing that case and what it called a pattern of FBI surveillance, a coalition of leading national Muslim organizations has largely suspended contact with the bureau.

"It's a nonexistent relationship," said Agha Saeed, national chairman of the coalition, the American Muslim Task Force on Civil Rights and Elections.

Justice Department and FBI officials say the California case is not representative of their relations with Muslims and that they have gone to great lengths to maintain good relations with the Muslim community. They say they continue to work closely with Muslims in investigating violence and other hate crimes against them.

Holder highlighted those efforts Friday night before an audience of Muslims, including many legal and business community leaders, at the Westin San Francisco. He said Justice Department and FBI officials are working hard to engage the Muslim and Arab communities through an Arab/Muslim Engagement Advisory Group he established last year.