Metro transit police anti- terror teams and patrol officers will continue operating on a “heightened state of vigilance” this week, in connection with the anniversary of the killing of Osama Bin Laden, a Metro spokesman said.

Spokesman Dan Stessel said “there is no specific or credible threat.” However, he said al Queda has indicated interest in the past in anniversaries and significant dates.

As a result, he said, riders may recognize a greater presence of transit police officers in the system Wednesday, as part of an effort to provide greater vigilance and increased visibility.

Riders observing suspicious activities or unattended packages are, as always, urged to report them, Stessel said.