"We only cast short extras so it made our set look bigger," he told the LA Times in an interview.

"Anybody above 5ft 8, we didn't cast them. It's like we got an extra million dollars of value out of casting."

The Hollywood blockbuster, released 26 years ago next week, became the highest-earning film of all time - until Cameron beat his own record with Avatar in 2009.

The fictionalised retelling of the famous 1912 sinking cost a then record $200m (£159m) to produce because of the huge scale of the sets and sequences that needed complex engineering and massive resources.

But Cameron insisted he "never panicked... the studio panicked. It's our job not to panic."

One way in which Cameron and producer Jon Landau cut costs during production was by scrapping an entire set planned to be tilted at a three-degree angle - which they said saved $750,000 (£600,000)

The producers made do with two sets, one for pre-iceberg scenes that was level, and a second, tilted at a six-degree angle to replicate the sinking of the ship after it hit the iceberg.

"If the studio had had their way, they would have cut the entire ship sinking," Cameron said.

"The smartest thing we did was do the sinking last. It wasn't because of strategy - it was simply because you sink the set last because otherwise it doesn't look so good the next morning when you bring it back up."

The director also admitted there were miscalculations in logistics even before the cameras rolled.

"It was hundreds of miles of cabling, all the Musco lights [sports lighting] in Hollywood at the time," Cameron said.

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"The scale of everything was beyond anything we could imagine in terms of our prior experience.

"At the time we thought, wow, there's no way this movie could ever make its money back. It's just impossible. Well, guess what?"

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Titanic took more than $1.8bn (£1.4bn) during its initial run, and that figure has grown to $2.2bn (£1.7bn) with subsequent re-releases, Box Office Mojo said.

The movie was nominated for 14 Oscars and won 11, including Best Picture.