A trader points up at a display on the floor of the New York Stock Exchange, Aug. 20, 2012. Reuters/Brendan McDermid

As the U.S. Justice Department was announcing a lawsuit to block the proposed Anthem-Cigna and Aetna-Humana mergers, Aetna CEO Mark Bertolini blasted out a company-wide email to employees saying that the company would fight the lawsuit in court. In the email, which was obtained by International Business Times, Bertolini assures employees that "we will continue to press forward" with the merger and that "our integration planning continues." The full email from Bertolini to Aetna employees can be read here:

Dear Aetna Employees,

We have learned that the Department of Justice is suing to block our proposed acquisition of Humana. Aetna and Humana will defend themselves vigorously in the lawsuit, and we remain firm in our belief that bringing the two companies together is in the best interest of consumers, particularly seniors.

From the day we announced the transaction, we have said that a combined company would result in a broader choice of products, access to higher quality and more affordable care, and a better overall experience for consumers. We still believe that to be true.

We look forward to sharing the facts in court, and we will continue to press forward. In the meantime, our integration planning continues. I would like to thank all those who continue working to close the deal and plan for a successful combination of our companies. And I would like to thank you for continuing to deliver for our members today - and every day - as we advance our mission of building a healthier world.

I will be hosting a town hall meeting on Monday, to which you will receive an invitation shortly. The press release we issued in response to the lawsuit can be found here. For additional information, please visit AetNet.

Mark Bertolini

Chairman and CEO