UPS Inc. and TNT Express said today they have offered to sell assets and to allow rivals access to their air networks in an effort to win approval from skeptical European regulators of UPS' proposed $6.8 billion purchase of Netherlands-based TNT.

In a statement issued today, the companies said their proposal would involve the combination of a "sale of business activities and assets" with "granting access to air capabilities." Neither company would provide details on the plan.

In the statement, UPS and TNT Express said any eligible buyers "will have to ensure the long-term viability of the divested activities and continuation of customer service." As part of the process, the European Commission (EC), the executive body of the European Union, will "market-test" the proposals to see if they pass muster with regulators, the companies said.

In late October, regulators furnished UPS and TNT Express with a "statement of objections" to the deal. At the time, the companies said they would craft a response within a couple of weeks.

Due to the timing of today's proposal, the EC has extended its review period of the deal from mid-January to Feb. 5.

The practice of carriers selling aircraft space to competitors is not new. "It's been a constant in the air business forever," said Jerry Hempstead, a former top U.S. sales executive with the former Airborne Express and DHL Express and now head of a parcel consulting firm bearing his name.

The acquisition, which was formally agreed to on March 19, has run into increasing regulatory headwinds in Europe as the year has progressed. Initially, UPS had set an Aug. 31 deadline to complete the transaction and had expected little, if any, regulatory resistance. However, the Atlanta-based company pushed back the deadline first to Nov. 9, and then to early next year, due to the EC's concerns over the deal's competitive effect on Europe's international express market.

In a Nov. 2 speech, EU Competition Commissioner Joaquin Almunia said the transaction requires "substantial remedies" to eliminate antitrust issues.

Perhaps in a bid to quell concerns that UPS will get so weary of the ordeal that it will walk away, the companies said today that they remain committed to the transaction. They said it would create a more efficient logistics market in Europe and enhance service solutions to businesses and consumers. The companies said they still anticipate an early 2013 closing date. The proposal to the EC does not alter the buy-out offer's existing terms and conditions, the companies said.

It is estimated that UPS and TNT Express combined control between 30 and 32 percent of the European parcel market. According to estimates from New York investment firm Wolfe Trahan & Co., TNT leads the market with an 18-percent share, followed by DHL Express with 16 percent, UPS with 14 percent, and FedEx Corp. with 4 percent.

There has been speculation that UPS' real objective in buying TNT Express was to prevent its chief rival, FedEx Corp., from again establishing a major foothold in Europe. FedEx once had an extensive intra-European operation, but in 1992 it withdrew from all but the continent's major commerce centers, citing spiraling costs and disappointing intra-European demand.

FedEx has expressed no interest in a counter-offer for TNT Express, saying it could grow adequately in Europe through organic expansion and smaller, more targeted acquisitions.