June 12 (Reuters) - A month-long lockout at the fourth-largest aluminum smelter in the United States ended on Thursday after unionized workers voted to ratify a new five-year labor deal with Century Aluminum, the union said on its website.

The United Steelworkers Local 9423 and Century, controlled by Swiss commodities trade house Glencore, resumed negotiations last week over a labor deal at the 244,000 tonne-per-year Hawesville, Kentucky, smelter.

Workers approved the deal by a 68 percent 'yes' vote.

(Reporting by Luc Cohen in NEW YORK. Additional reporting by Melanie Burton in MELBOURNE; Editing by Tom Hogue)