The FBI is offering to help people become US citizens in return for terrorism tip-offs.
US Attorney General Mr John Ashcroft says the initiative reaches out to "freedom-loving" people of all nations.
Information about terrorist activity will be rewarded with a three-year visa, immigration benefits and help applying for citizenship.
Mr Ashcroft revealed details of the Responsible Co-operators Programme at a Justice Department briefing.
He said: "We are asking all non-US citizens who are present in the US or who seek to enter it to come forward to the FBI with valuable information. "In return, we will help them make America their home."
He said members of the al-Qaida terrorist network are believed to be operating in the US, and non-citizens are often in a position to spot the warning signs.
Mr Ashcroft said: "The people who have the courage to make the right choice deserve to be welcomed as guests in our country, and perhaps one day to become fellow citizens."