The tombs -containing skeletal remains, ceramics, textiles and gold-plated copper pieces- are thought to be of a pre-hispanic Sican descent.
Last December, just after Christmas, workers involved in the Olmos irrigation project found 12 other tombs and since then, the site has been excavated by an archaeological service company.
"At the moment, specialists have discovered between 35 to 40 tombs which are undergoing a process of conservation and consolidation. Archaeological material related with these tombs has also been discovered," said site supervisor Humberto Salini.
"Basically, ceramics and what you can see was discovered in the lower part of what is a path," he told Global News Channel.
Experts will now transfer the remains to the Culture Ministry for further analysis, Ibtimes.co.uk reported, citing Lima daily El comercio.
The Sican culture, which lived on Peru's north coast between 750 and 1375 AD, preceded the Incan empire and its early period lasted until around 900 AD.