The government has decided to re-open for negotiations a benchmark power tariff of 3.1 cents per unit for private hydro-electric power projects because of refusal by international financial institutions to fund projects with unviable rates of return, sources have said. The sources said the government would approach foreign sponsors of four hydropower projects with total generation capacity of 1,010mw and estimated investment of about $2 billion for renegotiation of their respective tariffs.