MEXICO CITY, Aug 12 (Reuters) - Silver and gold producer Fresnillo on Wednesday denied media reports that thieves had stolen around 300 kilograms of gold from one of its mines in northern Mexico, saying the true figure was 4.5 kilograms of gold and silver worth about $165,000.

Fresnillo, which mines silver and gold from six mines in Mexico and is controlled by mining giant Penoles, said it was cooperating with authorities investigating the theft from its Herradura mine in the northern Mexican state of Sonora.

The company said nobody was injured in the heist but gave no further details. Mexican media reports on Wednesday said thieves stole around 300 kilograms of gold.

In April, armed robbers made off with 7,000 ounces of gold contained in some 900 kilograms of gold-bearing concentrate from McEwen Mining Inc's El Gallo 1 mine in Mexico.

The haul was worth about $8 million, McEwen Mining said.

According to Fresnillo, the Herradura mine employs more than 1,500 people and produced 98,359 ounces of gold in the first quarter of 2015. It has reserves of 5.3 million ounces of gold.

(Reporting by Gabriel Stargardter; Editing by Jonathan Oatis)