* Delay would avoid 1st quarter results period

* Source: Treasury still mulling stress test disclosure (Adds details on stress tests, byline)

By Karey Wutkowski

WASHINGTON, April 7 (Reuters) - The U.S. Treasury Department is planning to delay the release of any completed bank stress test results until after the first-quarter earnings season to avoid complicating stock market reaction, a source familiar with Treasury's discussions said on Tuesday.

The Treasury is still talking about how results of the regulatory stress tests on the 19 largest U.S. banks will be released, and may disclose them as summary results that are not institution-specific, the source said.

The government is testing how the largest banks would fare under more adverse economic conditions than are expected in an attempt to assess the firms' capital needs. The tests are due to be completed by the end of April, but Treasury has said they may be finished before then.

The source, speaking anonymously because the Treasury has not made a final decision on what to disclose, said officials do not want any test results released before the earnings season wraps up for most U.S. banks on April 24.

Treasury did not immediately respond to a request for comment.

U.S. regulators have reached the closing phase of the stress tests, with many of the top banks having already turned in their internal versions of the test to officials. Bank of America Corp (BAC.N: Quote, Profile, Research) Chief Executive Kenneth Lewis said last Thursday that his bank has already completed its test.