Titanic, released in 1997, is still the world's biggest-grossing film at US$1.8 billion ($4.18 billion), when inflation is not taken into account.
Fellowship has so far earned $1.6 billion worldwide.
Latest figures show the film climbed back to number one and took $283,671 in the week ending March 6.
The recent success at the Bafta awards helped The Fellowship to reclaim the top ranking, the spokeswoman said.
Box office takings should "improve substantially" with the Academy Awards coming up in two weeks.
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