The US has boosted its security presence and tactics in Washington and New York amid fears of a "credible terror threat" meant to coincide with the 10th anniversary of the September 11, 2001, attacks.<br /><br />The increased security came as Ray Kelly, head of the New York Police Department, has been accused by civil rights groups of over-stepping the department's jurisdiction by using its ties with intelligence services to illegally obtain information.<br /><br />Among the tactics that critics find controversial, the NYPD has sent undercover officers into predominantly Muslim areas to monitor communities, including listening to sermons at mosques.<br /><br />Speaking to Al Jazeera, Kelly denied the claims, saying his department's intelligence gathering was only used to protect the public.<br /><br />Al Jazeera correspondent Scott Heidler reports from New York.
