The wreckage of a missing Panther helicopter, which apparently "impacted the side of a mountain," was found in Jalisco, a state in western Mexico, the Navy Secretariat said Wednesday.

It is not known whether the four crewmen aboard the chopper, which went missing last Friday, survived the accident because search and rescue teams have not yet reached the crash site, navy spokesmen told Efe.

"The aircraft was spotted some 18 kilometers (11 miles) to the east of the city of Pihuamo" in a mountainous area, the secretariat said.

The Panther helicopter was carrying "a captain, two officers and an enlisted man," the navy said.

"The cause of the accident is not known, so the corresponding investigation will be carried out," the secretariat said.

Panther helicopters are used for "surveillance, transportation, exploration, search and rescue operations" by the navy, the secretariat said.

The chopper was flying on a route between Manzanillo, a city in Colima state, and Morelia, the capital of Michoacan state, on its way to the base in Minatitlan, a city in the eastern state of Veracruz, after taking part in a mission in the Pacific region, the secretariat said.

The navy and army have spearheaded the war that President Felipe Calderon declared on Mexico's drug cartels shortly after taking office in December 2006. EFE