A deadline for an earn-in agreement involving Australian-listed Medusa Mining and Sea Resources to explore the Prek Kampi region of Kratie province passed on Thursday with no deal being reached, according to a UK-based news website.

The two companies signed a memorandum of understanding in January to open up the possibility of Medusa earning a 70 percent stake by investing $3 million over the next four years; however, a March 1 deadline for such a deal was not met, according to the Proactive Investors website.

In its initial announcement, Medusa said it planned to look for copper, gold and oil in the region. Sea Resources was granted exclusive mining rights to the Prek Kampi region in June last year.

The area is home to the endangered Irrawady River Dolphin, although Medusa Mining CEO Boyd Timler previously said a potential mine would be unlikely to affect the dolphins, which reside in a stretch of the Mekong River about 35 kilometres west of the exploration area.

Representatives for Medusa Mining could not be reached yesterday.