* Local residents block mine's railway line
* Blockade began Monday, mine stocking mineral ore
LA PAZ, April 14 (Reuters) - Protests by local residents have blocked a key railway access to Bolivia's San Cristobal mine since Monday, forcing the mine, owned by Japan's Sumitomo Corp (8053.T), to store mineral ore on the site.
A San Cristobal official, who asked not to be named, said protesters have blocked a railway linking the mine with the main rail network.
"Company workers are not involved in the blockade. Local people are blocking," said the official, who the company has not authorized to speak publicly.
The official said the mine has been stocking mineral ore in containers since the blockade started, but did not say whether the mine was still able to export some ore by road or if any stocks were held in Chilean ports.
A Mining Ministry said he did not know the reason for the protest.
San Cristobal, in the central Potosi region, is one of the largest mines in Bolivia and produces silver, zinc and lead.
The mine is 100 percent owned by Japan's Sumitomo Corp. (Reporting by Diego Ore; Writing by Eduardo Garcia; Editing by David Gregorio)