In a reversal, the state government of Massachusetts has thrown its support to Microsoft in an ongoing battle over office software formats and has launched an investigation into the state’s former IT chief, who had been championing open-source software.

“The Commonwealth is very pleased with Microsoft’s progress in creating an open document format,” said the state’s Administration and Finance (A&F) Secretary Tom Trimarco in a short statement on Thanksgiving eve. “If Microsoft follows through as planned, we are optimistic that Office Open XML will meet our new standards for acceptable open formats.”

Previously, the administration of Governor Mitt Romney had proposed the exclusive use of the OpenDocument format, which has been vigorously opposed by Microsoft. The previous A&F Secretary, Eric Kriss, who was instrumental in fostering the OpenDocument policy. Kriss has left his position, leaving the state’s director of Informational Technology Division, Peter Quinn, without top-level support.

Romney, a Republican who is expected to announce a run for the Presidency, has seen his support for Microsoft buttressed by leading Democrats including Secretary of State William Galvin and influential state senator Marc Pacheco.

In a front-page story, The Boston Globe said Quinn is being investigated for attending out-of-state conferences that were sponsored by technology and information companies. The Globe quoted two unnamed “Romney administration officials” who said Trimarco wants to know details of Quinn’s trips. The Globe said the investigation was launched after it made inquiries about Quinn’s trips and whether they violated state conflict-of-interest regulations.

Some sources said Quinn’s trips had been approved by Kriss and Quinn has noted he has been in demand as a speaker at computer conferences because of the interest in the state’s debate over the formats.

Kriss and Quinn have supported an “Open Standards, Open Source” policy, arguing that it would open up the state’s office software business to increased competition. Supporters of Microsoft maintain that that stance would unfairly shut out Microsoft from state business.