A popular Upper West Side restaurant was trashed by vandals who scrawled anti-Semitic graffiti on the walls — and cops yesterday were investigating whether a disgruntled ex-worker was to blame, sources said.

“It was like someone came in and went wilding. Vandalism is one thing, but it was a total defacement. They urinated everywhere,” said David Ruggerio, 50, owner of Lansky’s Old World Deli on Columbus Avenue.

“They smashed all the computers, smashed phones, broke every plate in the place, sliced every banquette,” said the former Food Network star, adding that the vandals also swiped a register with an undisclosed amount of cash.

Ruggerio shut down the diner, a local fave, Wednesday after finding the mess.

He said the fiends caused about $200,000 in damage to the 5-year-old restaurant, between West 70th and 71st streets, and wrote anti-Semitic slurs on the walls in marker.

“I’m an Italian-American from Brooklyn, but if I was Jewish, I’d be deeply offended,” he fumed.

There were “some words, some symbols — I can’t tell you what they were. I don’t want this to become inflamed. I immediately covered them up.”

There was also a message that read “NOPOLR,” with capital A’s in the two O’s and the word “California” beneath it. Ruggerio had it seen before.

About two weeks ago, he let a dishwasher go after two days and the ex-worker and a female pal later broke into the deli, slept there overnight and cooked themselves breakfast in the morning.

Ruggerio found the same message, which police sources said didn’t appear to be gang-related, scrawled in the deli afterward.

“I knew something was wrong with him. Something was visibly wrong with him,” he said of the unidentified dishwasher.

The sources confirmed detectives are looking at the vandalism and burglary as “an inside job.”

Ruggerio hoped to reopen in time for today’s dinner crowd.

Lansky’s menu features a combination of Jewish deli favorites such as matzo ball soup and chopped liver as well as continental dishes like steak Diane and salmon picatta.

Ruggerio wrote the cookbooks “David Ruggerio’s Italian Kitchen” and “Little Italy,” which was made into a PBS series in 1999. The Food Network aired his show “Ruggerio To Go” a year earlier.

But he’s also had a checkered history in the restaurant business.

A restaurant that hired him as executive chef, Uncle Bacala’s in Garden City Park, LI, was evicted in 2006 for failing to pay about $48,000 in back rent.

And in 1999 he pleaded guilty to padding customers’ credit-card bills with about $100,000 in phony tips.

Before that, he was a top chef in Manhattan, where he owned Le Chantilly and cooked at and Maxim’s and La Caravelle.