Brussels-based DHL fueled fires over the issue of national ownership and control of U.S. air carriers last week, agreeing to merge with Airborne Express, spin off its ABX Air division and acquire the company's extensive ground delivery network for $1.05 billion.

The plan offered by DHL, a wholly owned subsidiary of Deutsche Post, the German post office, riled giant U.S. competitors FedEx and UPS. The rivals pledged to continue their two-year-long fight to prove that DHL is violating U.S. laws that limit foreign ownership and control of a U.S. airline.

A review of the competitors' case against DHL Airways, a subsidiary of DHL Worldwide Express and a certificated U.S. carrier, is pending at the U.S. Transportation Dept. In the wake of the DHL-Airborne merger proposal, UPS late last week asked for an "immediate inquiry" into the transaction. A FedEx official said the express operator agreed that an inquiry was needed.

DHL OFFICIALS said they will spin off ABX Air Inc. as a public company, a move that is raising questions about the survivability of either ABX Air or DHL Airways, which hold minority market shares in the air express industry. The main hubs of the two carriers are less than 50 mi. apart in the Ohio River Valley. Airborne's ABX Air operates the U.S.' largest privately held airport facility, a two-runway former Strategic Air Command base at Wilmington, Ohio. DHL Airways is preparing to open this summer a $300-million new facility at the Cincinnati/Northern Kentucky International Airport.

The Wilmington airport has an edge over the Cincinnati hub as an operating facility, said David Hoppin, principal with MergeGlobal Inc., an Arlington, Va., consulting firm. Hoppin said DHL, if it is working with ABX, will be able to "control it all" at Wilmington, where Airborne is the exclusive operator. But one source close to the DHL operation said Airborne's remote Wilmington location requires employees to be bused, which could be regarded as a disadvantage.