United States-based airlines have begun to withdraw a revenue-boosting fare increase initiated last week, but it is too soon to say whether the bulk of the increase will last, a fare tracker said yesterday.

Even Delta Airlines, the No. 3 U.S. carrier, rolled back 10 per cent of its fare increase, Rick Seaney, chief executive of FareCompare.com, said in a research note.

"This activity mostly reflects on the competitive pressures of low-cost airlines, which have not yet joined into the increase," Seaney said.

Delta raised ticket prices last Thursday by US$5 each way on domestic routes to offset rising costs. The increase followed one launched by Southwest Airlines, which frequently spoils fare increases by failing to match.

Delta's increase represents a test of pricing power at the start of the seasonally weak autumn travel period, when demand generally falls off.

The airline industry has been battered in recent years by soaring fuel prices and competition. Carriers managed to cut capacity in 2006 and begin a trend toward higher fares. The trend continued, but slowed, in 2007.

- Reuters