The charges are tied to a technology transfer deal signed between Patria's Vammas division and a company owned by the Egyptian Ministry of Military Production in 1999.
The contract laid the groundwork for manufacture of a Finnish-designed howitzer in Egypt.
The prosecutor says there is reason to suspect that representatives of the Finnish company gave substantial bribes to Egyptian officials, apparently through an Egyptian agent.
Patria has dismissed the charges as groundless.
The work of police and the prosecutor has been hampered by Egyptian officials' refusal to assist them with the case.
In 2005, Patria Vammas was re-named Patria Weapon Systems, which in 2008 was folded into another subsidiary called Patria Land & Armament. The charges cover events between 1999 and 2007.
The Finnish State owns about 73 percent of Patria, with the remainder held by the European consortium EADS.