(Adds 9 bodies found in Hidalgo municipality)
MEXICO CITY, May 19 (Reuters) - Mexican authorities said on Monday they had found 16 bodies in the northern state of Tamaulipas, where a battle between drug gangs has sparked a wave of bloody shootouts and massacres.
The bodies of four men and three women who have not yet been identified were found late Sunday in a light truck in the port city of Tampico, according to a government task force set up last month to respond to the spike in violence across the state.
In a separate incident, nine more bodies - five male and four female - were found beside three burned out homes in the municipality of Hidalgo near the state border with Nuevo Leon, the state government said.
Mexico's feared Gulf cartel has been battling the Zetas over control of drug and migrant smuggling routes around Nuevo Laredo, the biggest border crossing for trade between the United States and Mexico.
Tamaulipas houses vast deposits of shale resources and major energy installations, including the smallest of the country's six oil refineries.
President Enrique Peña Nieto is trying to rein in drug violence, which has claimed the lives of more than 90,000 Mexicans since former president Felipe Calderon sent out the military to fight gangs at the end of 2006.
Peña Nieto ordered a task force of federal and state officials in April to take over security operations in Tamaulipas amid concerns about corruption among local security forces who were failing to stop a surge in violence.
Earlier this month, a commander of a new elite investigative unit was killed by other police just two months after assuming his post. (Reporting by Lizbeth Diaz and Noe Torres; Writing by Michael O'Boyle and Alexandra Alper; Editing by Chris Reese and Ken Wills)