UPDATE 1-Walgreens in talks to buy AmerisourceBergen -WSJ

(Adds AmerisourceBergen response, background, updates shares)

Feb 12 (Reuters) - Drugstore operator Walgreens Boots Alliance Inc has made a takeover approach to drug distributor AmerisourceBergen Corp, the Wall Street Journal reported on Monday.

Amerisource shares rose 15 percent in after-hours trading.

Representatives of Walgreens' Chief Executive Stefano Pessina made "a high-level outreach" to representatives of Amerisource CEO Steven Collis several weeks ago, the WSJ said, citing people familiar with the matter. http://on.wsj.com/2Ch5Gg9

The two companies discussed the possibility of Walgreens buying the portion of Amerisource that it does not already own, the paper reported.

AmerisourceBergen said it did not discuss any rumors or speculation regarding potential mergers or acquisitions.

Walgreens, which owns about 26 percent of Amerisource, was not available for comment outside regular U.S. business hours.

Healthcare payers and pharmacies are responding to a shifting landscape, including changes in the U.S. Affordable Care Act, rising drug prices and the threat of competition from online retailers such as Amazon.com Inc.

The healthcare industry is seeing a wave of consolidation, including CVS Health Corp's acquisition of health insurer Aetna Inc.

The $69 billion deal was seen as likely to pressure rival insurers, drugmakers, pharmaceutical benefits managers and retail pharmacies to consider mergers or switching partners to try to keep up with the potential healthcare cost savings or increase in profit margins.

(Reporting by Rishika Chatterjee; Editing by Rosalba O'Brien and Peter Cooney)