(Adds detail about other airlines' service cuts)
NEW YORK, July 11 (Reuters) - United Continental Holdings Inc said on Friday it would drop its daily flight to Caracas, Venezuela, from Houston, starting in September, joining other U.S. carriers who have cut service over the country's foreign exchange controls.
United said it will operate four flights a week to the country, starting Sept. 17.
On Monday, Delta Air Lines Inc said it would run a single flight a week to Caracas, down from one a day, starting Aug. 1, because of the currency problem.
American Airlines Group Inc announced a similar move last month, cutting to 10 flights a week from 48, a decline of nearly 80 percent in its schedule that left Miami as the only U.S. destination. The change took effect July 2.
Venezuela requires airlines to sell tickets using the local bolivar currency, but carriers say they are not receiving approval from the exchange control board to convert those earnings into dollars.
Airlines have an estimated $4 billion in revenue stuck in the country because of approval delays, according to the International Airline Transport Association.
(Reporting by Alwyn Scott; Editing by Chris Reese and Andre Grenon)