An arbitrator ruled that United Continental Holdings cannot use Continental's codes for 70-seat jets operated by its regional partners since a labor contract requires them to be flown by Continental pilots.

Continental's pilots had disputed United's plans to use regional partners on dozens of flights with 51 or more seats, and arbitrator Richard Bloch sided with the pilots in a decision issued on Thursday.

Affected routes included commuter flights from airports like Newark and Houston.

United said in an e-mailed statement that it disagrees with the arbitrator's decision, but will comply with the ruling.

We are pleased that this decision will permit the company to redeploy 70-seat aircraft in certain markets under the United Express brand to better meet demand and improve profitability of the combined company, the company said.

United Airlines parent UAL Corp and Continental merged in October to form the world's largest airline, but they continue to function separately while they pursue a single operating certificate from the U.S. government.

(Reporting by Deena Beasley, editing by Dave Zimmerman)