Delta Air Lines Inc. will ask its board members on Friday to discuss a possible merger with United Airlines and Northwest Airlines. Sources close to the company said Chief Executive Richard Anderson is trying to gain authority to converse with the airlines because their route networks complement Delta's.

After emerging from bankruptcy last spring from bankruptcy last spring post the denial of a hostile takeover bid by US Airways Group Inc., Delta, in November said that a special committee was formed by its board of directors to work with management in order to review and analyze strategic options, including business mergers.

The carrier was not divulging any details on the committee’s work, while it is in progress, said Betsy Talton, a spokeswoman for Delta.

“Delta's formation of a special committee to evaluate possible business combinations is a strong indication that (UAL) and Delta are in active discussions,” said credit rating firm Egan-Jones. “However, a number of hurdles, mainly in the regulatory side, remain before completion of any deal.” It added, “If a deal with Delta does not happen, we expect other combinations," for UAL.

Delta ranks third among the carriers in the U.S. while United and Northwest are No. two and five respectively. A successful merger of the former with either of the latter would produce the largest airline, displacing the No.1 American Airlines.

Based on the present market values, acquisition of either airline by Delta would be worth at least $3.5 billion.

Shares soared in afternoon trade, Delta was up 14.6 percent to $15.50, Northwest surged 23.2 percent to $14.80, and UAL gained 19.1 percent to $31.00.