WASHINGTON, Jan. 25 (Xinhuanet) -- The reported terrorist plot against Boston last week was a false alarm, said the US Federal Bureau of Investigation (FBI) Tuesday.

    "It has been determined that the threat had no credibility," the FBI said in a statement, about one week after the unconfirmed threat was first reported.

    "While the threat information proceeded from criminal activity there were in fact no terrorist plans or activity under way," it said.

    The FBI made the announcement after questioning Mei Xia Dong, aChinese woman, one of 14 persons initially thought to be involved in the alleged plot.

    The woman was found to be at a US Customs and Border Protectiondetention facility in California after her name was released last week.

    The FBI said the woman, who was arrested for an immigration violation in November last year, may have entered the United States for "economic reasons."

    Last Monday an anonymous man called into the California HighwayPatrol saying that four Chinese and two Iraqis have entered into the United States from Mexico, and that they were waiting a shipment of nuclear material and brought them to Boston.

    The call prompted Boston authorities to boost security and postleaflets with pictures of four of the "persons of interest," so asto crush a possible plot to set off a nuclear blast, said local media last week.

    A Mexican official said the tipster was one of the two smugglers allegedly involved in moving the 14 Chinese migrants across the border, and he wrangled over a deal with his confederate and called the false tip as a revenge.

    The two smugglers had been detained and were being questioned by the FBI. Enditem