Study says many plots have been thwarted by members of Islamic community as rights groups call for cancellation of congressional hearings.
American Muslims arrested on terror charges down sharply
The report from the Triangle Centre on Terrorism and Homeland Security at the University of North Carolina Chapel Hill includes data on individuals involved in terrorism in the United States or abroad since the September 11 attacks.
The findings run counter to many US media reports on the scale of home-grown Islamic terrorism and provides fresh impetus to religious and civil rights groups working to prevent the demonisation of American Muslims.
David Schanzer, director of the centre, said the study "puts into perspective the threat presented by domestic radicalisation of Muslim Americans."
"Is this a problem that deserves the attention of law enforcement and the Muslim American community? Absolutely" he said. "But Americans should take note that these crimes are being perpetrated by a handful of people who actions are denounced and rejected by virtually all the Muslims living in the United States."
Several high-profile attacks have dominated the headlines in recent years, such as the killing of 13 people at Fort Hood, Texas, in 2009 or the failed Times Square bombing last year.
But less noticed is the cooperation offered by many American Muslims to law enforcement agencies in order to prevent such attacks, according to the report.
The study said tip-offs from the American Muslim community provided the source of information that led to a terrorist plot being thwarted in 48 of 120 cases involving American Muslims since the attacks of September 11, 2001.
"Muslim-American terrorism makes news," said the report, called "Muslim American Terrorism Since 9/11: An Accounting". "Out of the thousands of acts of violence that occur in the United States each year, an efficient system of government prosecution and media coverage brings Muslim-American terrorism suspects to national attention, creating the impression - perhaps unintentionally - that Muslim-American terrorism is more prevalent than it really is."
The study noted that while there have been approximately 150,000 murders in the US since 9/11, terrorist attacks carried out by 11 American Muslims during the same period in the US killed 33 people, or about three deaths per year.
The number of American Muslims engaged in terrorist acts on domestic targets declined from 18 in 2009 to 10 in 2010. Meanwhile, a majority of terrorist activities took place outside the US. The higher figure for 2009 included 17 Somali-Americans who joined the Al Shabab Islamist movement, which is linked to al Qa'eda.
Charles Kurzman, the study's author and professor of sociology at the University of North Carolina Chapel Hill, said: "Of course, even a single terrorist plot is too many. But this trend offers a challenge for the American public: if we ratchet up our security concerns when the rate of terrorism rises, should we ratchet down our concerns when it falls?"
Mr Kurzman said his new book, called The Missing Martyrs: Why There Are So Few Muslim Terrorists, to be published in June, would explain that "western concerns over Islamist terrorism seem to be out of proportion to the actual number of attacks."
"Most Muslims don't want what the revolutionaries are selling. Most don't want to engage in revolutionary violence.," he said. "Of those who do want it, fear of security forces or other reasons see them staying out of the fray. Those who do sympathise mostly do so because they are anti-imperialist."
He compared those who flirted with jihadi opinions on internet chat rooms and other forums to "radical chic" college students who put up posters of Che Guevara, the Marxist revolutionary, but did not actually want to see a Stalinist or socialist state come into being.
On Monday, a coalition of 51 US civil rights groups sent a letter calling on congressional leaders to either cancel or broaden expected hearings on American-Muslim extremism. The hearings have been called by Peter King, a New York Republican and chairman of the committee on homeland security in the House of Representatives, who has so far refused to change the scope of his investigation to include terrorist acts committed by non-Muslims.
The letter, which was signed by a wide range of groups including the Council on American Islamic Relations and Amnesty International USA, said: "These hearings will almost certainly increase widespread suspicion and mistrust of the American Muslim community and stoke anti-Muslim sentiment. During 2010, we saw an increase in anti-Muslim hatred in public discourse, as well as hate crimes and violence targeting American Muslims, and those perceived to be Muslim, including vandalism and arson of mosques, physical attacks, bullying of children in schools, and attempted murder."
The coalition's call has support from Bennie Thompson, a Mississippi Democrat, who said that Jared Lee Loughner, the alleged shooter of Gabrielle Giffords, a Democrat, in Arizona last month was not Muslim.
"Attacks are just as likely to come from lone-wolf extremists - like James Wenneker von Brunn, the Holocaust Memorial Museum [in Washington in 2009] shooter, or Jared Lee Loughner, who is charged with the tragedy in Tucson, Arizona - as they are from Muslim extremist groups," Mr Thompson wrote last month in Politico, a Washington-based newspaper.