An inferno erupted near the top of a Manhattan high-rise on Christmas morning, killing a longtime New York City designer, officials said.

Fire officials said smoking was to blame for the blaze.

Flames could be seen shooting from the 35th floor of the Carnegie Mews Apartments on West 56th Street, a block from Carnegie Hall, at around 7:30 a.m. Monday.

John Doktor, 76, who lived in the unit where the fire broke out, was found dead by firefighters who rushed to the scene.

A friend of the victim told The Post that Doktor was a designer who worked for Anne Klein Studios.

“Right now, it’s all a mystery and we’re waiting to hear back from the detectives,” said a pal, Francine Fish, who lives in Florida.

“He was a wonderful person and he was very talented. I’ve known him all his life. I’m still in shock he’s gone.

“It’s just terrible,” she continued. “And to have to give people this news today is even worse.”

Comedian Jackie Mason’s daughter, Sheba, 31, who lives on the sixth floor of the building, said she was abruptly awakened and told to rush out.

“I’m wearing my pajamas,” she said over the blare of sirens.

Other residents complained that they hadn’t been alerted of the fatal blaze by management.

“We could have all been killed while we were sleeping in our beds,” fumed a man who gave his name as Tony and who said he lives on the 10th floor.

“There should be an alarm system. I mean, damn,” the 49-year-old complained.

Assistant Fire Chief Joe Woznica said harsh winds made the blaze difficult to contain.

“Due to the extreme winds . . . it was pretty rough, pretty hot and dangerous,” he said.

Woznica also said the building’s elevators were slow and delayed firefighters.

“Due to the speed at which the elevators operated, it caused a slight delay getting the hose lines into position,” he added.

Firefighters traveled by elevator to the 25th floor but got out and took the stairs the rest of the way.

“[It’s] not a good way to start Christmas for anyone,” one firefighter said as he was exiting the building.

Building management did not immediately return messages seeking comment on the elevator situation.

Two firefighters were injured, according to authorities.

Meanwhile, another blaze broke out in Chelsea later in the day. The flames, which raged just steps from a local fire station, broke out at around 3:30 p.m. on the top floor of 144 W. 19th St. near Seventh Avenue.

The fire lapped up the side of the building and went through the roof.

Resident Smrithi Hariharan said she was walking back to her apartment when she saw the blaze.

“Flames were just licking at the window at first and then more things started exploding,” Hariharan said. “We were just confused, like . . . that’s my building.

“We have a cat up there. We call him Cat. They can’t tell us anything, but, yes, I’m worried.”

The cause of the Chelsea fire was not immediately clear. Only minor injuries were reported.

The city issued a permit for emergency replacement of gas piping on Nov. 14 for that building, according to public records.

Additional reporting by Joseph Marino, Tamar Lapinand Emily Saul