New Yorkers can now warn authorities of suspect activities with a tap, thanks to a smartphone phone app to fight terror unveiled Monday on the eve of the US Thanksgiving holiday.

With "See Something, Send Something," people in New York state can quickly send information, be it a short text or photograph, to the New York State Intelligence Center.

Once the app launches on their phones, users must enter their name and phone number and can then send the information right away.

"Please send a note with as much detail as possible," it asks for users sending messages.

Governor Andrew Cuomo also announced that the Metropolitan Transit Authority was hiring 46 police officers to boost the counterterrorism capacity of public transportation, including at the Grand Central and Penn rail stations.

"These new efforts are essential pieces in our fight against terrorism," Cuomo said in a statement.

"We have stepped up our preparedness in the aftermath of the Paris attacks, and we continue to remain vigilant against those who seek to spread fear and violence," he added, referring to the November 13 assault on the French capital.