PORTLAND — Unum Group, which employs some 3,100 people in Maine, reported net income of $205.6 million or 69 cents per diluted share during the third quarter of 2011, compared to $220.8 million or 68 cents per share in the same period last year.

“While our performance was slighlty below expectations, I am generally pleased with our results, particularly given the challenging economic environment,” said President and CEO Thomas Watjen in a letter to employees released today. “Although we face challenges, we are fortunate to be in a very strong business and financial position, and therefore we should remain confident in our future.”

The Chattanooga, Tenn.-based company, which sells disability, life, dental, long-term and other types of insurance, reported after-tax operating income of $221.5 million or 74 cents per share in the third quarter, up from $219.9 million or 68 cents per share in the third quarter 2010.

Operating income from Unum’s UK division took the hardest hit during the quarter, dropping 26.1 percent, to $34.9 million.