By Jim Finkle and James Pearson

NEW YORK/SEOUL, Dec 10 (Reuters) - Sony Corp. Chief Executive Kazuo Hirai ordered the film "The Interview" to be toned down after Pyongyang denounced it for depicting the assassination of North Korea's leader, according to emails apparently stolen from Sony's Hollywood studio.

The comedy, slated for U.S. release on Dec. 25, is about journalists played by Seth Rogen and James Franco who are hired by the CIA to kill North Korean leader Kim Jong Un.

According to emails that span from August through October and were obtained by Reuters, Hirai asked Amy Pascal, co-chairman of Sony Pictures Entertainment, to change a key shot in the film. It depicts Kim struck by a tank shell, causing his head to explode.

Pascal noted to Hirai that she had encountered resistance from the film's creators, including Rogen, who wrote and co-directed it.

Hirai's interest in the film shows the company's leadership was worried about Pyongyang's objections, even before a devastating cyber attack on Sony's Hollywood studio network last month that crippled most of it for more than a week.

A Sony Corp. official told Reuters that Hirai rarely reviews specific scenes in films.

North Korea complained to the United Nations in July, accusing the United States of sponsoring terrorism and committing an act of war by allowing production of the movie.

In an exchange with Rogen, Pascal said she was in a difficult position because Hirai had asked her to make changes in the film.

"And this isn't some flunky. It's the chairman of the entire Sony Corporation who I am dealing (with)," she said.

Rogen responded by promising to remove three of four burn marks on Kim's face, and reduce the "flaming hair" by 50 percent. But he said he could not meet all the demands.

"The head explosion can't be more obscured than it is because we honestly feel that if it's any more obscured, you won't be able to tell it's exploding and the joke won't work," he said.

Representatives for Rogen declined to comment.

Details of the emails were reported late on Tuesday by Bloomberg News.

More than 100 gigabytes of information purportedly stolen from Sony have been released on the Internet, according to cybersecurity experts, who say the documents appear to be authentic.

Rogen initially told Pascal he objected to requests to modify the death scene, which he said would be viewed as censorship and hurt sales.

"This is now a story of Americans changing their movie to make North Koreans happy," he said in an Aug. 15 email. "That is a very damning story."

By October, however, he delivered what he hoped was the final version.

"This is it!!! We removed the fire from the hair and the entire secondary wave of head chunks," he said. "Please tell us this is over now." (Additional reporting by Ritsuko Ando in Tokyo; Editing by Dan Grebler)