NEW YORK (Reuters) - Nearly 5.5 million customers remained without power in 14 U.S. East Coast states following Hurricane Irene, the Energy Department said on Monday.

Outages were most severe in New York state, which had about 940,000 customers without power, the department said.

It said Conoco's 238,000-barrels-per-day refinery in Linden, New Jersey remained offline on Monday.

(Reporting by Selam Gebrekidan and Joshua Schneyer)