MEXICO CITY, Oct 15 (Reuters) - Tropical Storm Rick formed off Mexico's Pacific coast on Thursday and could become a hurricane within the next day, the U.S. National Hurricane Center said.

Rick was located 345 miles (555 km) south-southeast of the resort city of Acapulco with maximum sustained winds near 50 mph (85 kph).

"Continued strengthening is forecast during the next 48 hours," the Miami-based hurricane center said.

Salina Cruz, Mexico's main oil-exporting port on the Pacific coast, was not in the path of the storm. Most of Mexico's oil installations are in the Gulf of Mexico.