Reuters Summit-UPDATE 2-Humana CEO: No regret on Medicare letter

* Humana CEO: Seniors need to know health plan impact

* Said letter complies with regulations

(Adds Medicare saying investigation closed, paragraphs 6-7)

By Lisa Richwine

NEW YORK, Nov 11 (Reuters) - Humana Inc (HUM.N) does not regret sending its Medicare customers a letter warning they could lose benefits under healthcare reform proposals circulating in Congress, the company's chief executive told Reuters on Wednesday.

The mailing prompted U.S. officials in September to probe whether Humana violated federal regulations with the letter to customers enrolled in the company's Medicare Advantage plans, a private alternative to traditional government-run Medicare coverage for the elderly and disabled.

Humana Chief Executive Mike McCallister, speaking at the Reuters Health Summit in New York, said it was important to inform seniors about proposals that could affect Medicare and he had "no regrets" about sending the letter.

"I've been accused of scaring seniors. I would argue ... I just gave them the facts, and the facts happen to be quite scary," McCallister said.