VIENNA—An Austrian court has found a former agent for Defense Contractor BAE Systems PLC guilty of tampering with evidence but innocent of the more serious charge of money laundering.

After pronouncing his verdict Thursday, Judge Stefan Apostol sentenced Count Alfons Mensdorff-Pouilly to a suspended two-month prison term.

Mensdorff-Pouilly was originally charged with paying out (EURO)12.6 million ($16.7 million) on behalf of BAE to contacts in Eastern and Central Europe in efforts to win contracts.

Prosecutor Michael Radasztics says he will appeal.

Mensdorff-Pouilly was charged in Britain in 2011 with conspiracy to corrupt in his efforts to secure contracts. But the charges were dropped after the company agreed to pay a multimillion-dollar fine to settle an arms export controls case with the U.S. Department of State.