Taliban insurgents attacked police checkpoints Sunday in volatile southern Afghanistan, killing at least 10 officers in the ongoing assault, authorities said.

Mohammad Ismail Hotaki, the director of Helmand province's Joint Coordination Office, said that Taliban fighters attacked 10 police checkpoints in the province's Sangin district. Hotaki said Taliban fighters captured three checkpoints and continued to surge forward in their assault.

Hotaki said the violence killed at least 10 officers and wounded 16. Later, Sangin's deputy police chief, Haji Bari, said authorities recovered the corpses of at least 13 slain police officers, while 15 had been wounded. Such contradictory casualty figures are common amid an ongoing attack.

"We are in control of 80 percent of the checkpoints and are currently fighting with Taliban at two checkpoints," Bari said. "The Taliban numbers are high and they are attacking with full force. This level of force shows they are in a strong position to fight back."

Afghan security forces have been battling the Taliban in Helmand province for almost three months after launching an operation aimed at showing their strength ahead of the insurgents' annual warm weather offensive. Since that offensive began April 24, the Taliban have launched a number of attacks across many parts of Afghanistan.

Police checkpoints are regular targets as they are often poorly manned and vulnerable. The high number of casualties suffered by police, who often bear the brunt of the fight against the Taliban without the same resources as the army, has damaged morale and created an impression of battlefield domination by the Taliban.

The offensive comes as NATO and U.S. troops ended their combat mission in the country at the end of last year, leaving the responsibility for the fight against the Taliban solely on the shoulders of local Afghan forces.