Mexico's Navy Secretariat has confirmed that all four crew members of a helicopter that crashed in the western state of Jalisco were found dead inside the wreckage.

In a brief statement, the secretariat said military investigators arrived at the crash site Thursday and located the dead bodies of the marines inside the Panther helicopter, which had gone missing on June 22.

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

The Navy Secretariat, which still has not determined the cause of the crash, lamented that "exemplary marines" were killed while carrying out their duties and expressed its condolences to their families.

The helicopter was being used by the marines for "surveillance, transportation, exploration, search and rescue operations," the secretariat said.

It added that the chopper was flying to the base of Minatitlan, a city in the Gulf coast state of Veracruz, after taking part in a mission in the Pacific region.

President Felipe Calderon gave marines, army soldiers and federal police the lead role in the battle against drug cartels shortly after taking office in December 2006. EFE