NEW YORK (AFP) - Two plainclothes New York police officers were shot late on Monday as they investigated a robbery, local media reported.

Their injuries were not life-threatening and the gunman apparently did not deliberately target them simply because they were police, the New York Times reported.

On Dec 20, two uniform-wearing officers in New York were shot by a black gunman claiming to be avenging the deaths of African-Americans during recent confrontations with police.

Local media said Monday's shooting happened as the two officers tried to stop a robbery in the Bronx. One was shot in the back, the other in the arm, the New York Daily News reported. Both officers were sent to the hospital.

New York's police department has been on edge since last month's shooting and officers have repeatedly shown their disdain for Mayor Bill de Blasio by turning their backs to him during public events, including the funerals of the two slain cops.

Some officers accuse de Blasio of inciting the shooting over remarks about police relations with black Americans and were enraged that he counsels his biracial son to be careful around officers.