ADDIS ABABA (Reuters) - Ethiopian Airlines on Saturday became the world's first carrier to resume flights with Boeing Co's 787 Dreamliner passenger jets, a Reuters witness said, three months after they were grounded over battery meltdowns.

U.S. regulators approved a new battery design last week, clearing the way for installation and a resumption of Dreamliner flights by international carriers.

Saturday's flight was the first since regulators grounded the worldwide Dreamliner fleet on January 16 after two lithium-ion battery meltdowns that occurred on two jets within two weeks that month.

The battery faults raised fears of a possible mid-air fire, drawing worldwide attention to Boeing and denting the reputation of its flagship plane.

"I'm always worried about flying and I'm an insurance worker so I'm apprehensive. But I'm sure they've checked and double checked so we'll be fine," said Eunice Mbogo minutes before boarding Ethiopia Airlines' Dreamliner flight to Nairobi.

The aircraft was due to land in Kenya just before 1000 GMT.

The grounding of the Dreamliner fleet has cost Boeing an estimated $600 million, halted deliveries and forced some airlines to lease alternative aircraft.

(Reporting By Aaron Maasho; writing by Drazen Jorgic; editing by Mark Heinrich)