MONTERREY (Reuters) - Three workers were injured at a new Kia Motors <000270.KS> factory in northern Mexico on Saturday, after one fell into a sewer ditch and two others attempted a rescue but were also hurt, the head of emergency services said.

Luis Felipe Puente, Mexico's national director of emergency services, told Reuters that no explosion had taken place and the workers were being treated at a local hospital.

A local emergency services official earlier said there had been an explosion, but later said that was not the case.

Kia Motors started production at the $1 billion factory last month and plans to increase its total production capacity to 300,000 vehicles a year, from this year's projected 100,000.

It is located just outside the industrial city of Monterrey in the town of Pesqueria.

A local spokesman for the South Korean carmaker did not immediately return calls seeking additional information.

(The story was refiled to reflect officials saying there was no explosion)

(Reporting by Gabriela Lopez in Monterrey, and David Alire Garcia and Luis Rojas in Mexico City; Editing by Cynthia Osterman and Mary Milliken)