There are signs that disgruntled officers have started making more low-level arrests, New York Police Department officials said Monday.

NYPD statistics show arrests were up in the past week after plummeting in the weeks following the fatal ambush of two patrolmen in December.

Ticketing for traffic and parking violations also increased after virtually coming to a halt.

Union officials have denied the numbers reflected a sanctioned work stoppage. But the numbers were seen as further evidence of growing rancor between the rank and file and Mayor Bill de Blasio.

The two patrolmen were killed Dec. 20 in a brazen daytime ambush. They were targeted by a mentally unstable man who vowed online to kill two “pigs” in retaliation for the deaths of black men and boys at the hands of police around the country. Police unions have accused de Blasio of contributing to anti-police sentiment by supporting protests over the police killings.

Continued concerns over the rift come at a time when the department also is taking precautions in response to the terrorist attack in Paris and reports of a renewed threat from the Islamic State group.

Police Commissioner William Bratton confirmed Monday that in the wake of the Paris killings, someone posted an Islamic State group propaganda video calling for the killing of “intelligence officers, police officers, soldiers, and civilians” in the United States — a message that first appeared online in September. The threat prompted the NYPD to send out a new safety alert advising officers working in pairs on fixed posts in patrol cars to make sure one stands outside of the car, Bratton said in an interview on CBS.

If both officers “are sitting in the car and they’re busy texting away or not paying attention of the surrounding area, they’re much more vulnerable to attack,” he said. “So it’s something that we continually try to drive home to our officers, that this is real. This is real and we need to be constantly vigilant.”

(AP)