An international arbitration tribunal has appointed judges to oversee a claim filed by a landowner, in a case which may force the government to clarify its ambiguous stance on the controversial expropriation of beachfront land in Playa Grande, Guanacaste.

Marion Unglaube and her husband Reinhard accuse the Costa Rican government of violating a Germany-Costa Rica bilateral investment treaty, by blocking them from developing a housing-tourism project along beachfront property on Playa Grande.

Grande is one of three adjoining beaches which make up the main Pacific nesting site of the critically endangered leatherback turtle.

The couple brought the claim before the International Centre for Settlement of Investment Disputes (ICSID), established by the World Bank in 1966 to address disputes between States and nationals of other States. More than 140 countries, including Costa Rica, have become contracting members.

The Unglaubes say their project — a 34-hectare (84 acres) property, comprising 60 houses, four hotels and a market begun in the 80s — has been on hold for more than five years.