The mayor of a town in Mexico's southwest has been stoned to death - the 11th municipal leader to be killed in the country this year, government officials say.

Gustavo Sanchez, the 29-year-old mayor of the Tancitaro, which lies around 300km west of Mexico City, was found dead along with a government colleague on a rural road on Tuesday morning, the officials said.

Sanchez's secretary, Rafael Equihua Cervantes, 36, the town council co-ordinator, was found with him and also believed to have been killed in the same manner.

Sanchez was named interim mayor of Tancitaro, a town of around 26,000 people in Michoacan state, in December after the previous mayor and city council resigned when they received death threats from drug trafficking gangs.

Jesus Montejano, the Michoacan state attorney general, confirmed the suspected nature of Sanchez and Cervantes' deaths, though Montejano's spokesman had earlier said both were believed to have been killed with machetes.

Montejano said he was concerned because the apparent stoning was "quite unlike what organised drug crime usually does".

In 2009, the chief of the city council, Gonzalo Paz, was kidnapped, tortured and killed. The mayor and town council subsequently resigned in December, and Sanchez fired the town's entire 60-officer police force, replacing them with federal officers.

Separately on Monday, Mexican officials said nine people were killed in two incidents of fighting between troops and armed men in the city of Reynosa in Tamaulipas state, on the border with the US.

Six armed men were killed during one confrontation, and one soldier and two armed men were killed in a second, the Mexican navy said.

Nine individuals accused of links to organised crime were arrested, the navy said.

The two raids also hauled in a large stash of weapons, including a range of guns, a rocket launcher, more than 4,000 bullets and several grenades.

Mexican troops also seized $60,000, 12 vehicles, and various military-style uniforms, the navy said.

Around 28,000 people have died in Mexico since Felipe Calderon, the country's president, launched a campaign against the drug traffickers, marked by his dispatching of 6,500 federal security forces to Michoacan in December 2006.

Source: Agencies