A "lone wolf Al Qaeda sympathiser" who plotted to bomb police cars and postal facilities in Manhattan as also US soldiers was arrested as he was preparing to create working explosives, officials said.

Jose Pimentel, 27, described as a "lone wolf" with no ties to international groups, planned to carry out a one-man terror spree in retaliation for the US killing of Qaeda cleric Anwar al-Awlaki in September, according to Police Commissioner Raymond Kelly.