Peru Copper Inc., Vancouver, British Columbia, said Tuesday that the net value of its Toromocho copper project in Peru has increased 13 percent to $922 million from $814 million.

The internal rate of return on the project also has risen to 16.7 percent from 16 percent following a pre-feasibility study, the junior copper miner said.

"We are pleased to see the positive impact on the pre-feasibility study of both new drilling information and further reserve and resource analysis reflected in the technical report," J. David Lowell, Peru Copper's executive chairman, said. "An additional $108 million in the estimated NPV (net present value) is an important improvement and we expect to see others as we continue to optimize the project."

Peru Copper announced earlier this month that the previously stated 1.26 billion tonnes of indicated copper resources at Toromocho had been classified as proven and probable reserves. An additional 715 million tonnes remained as measured and indicated resources, the company said.