Norway's contribution to the Tropical Forest Forever Facility (TFFF) would be conditional on at least 100 billion kroner ($9.8 billion) having been secured from other donors, according to a government statement.

Another condition is that Norway's contribution must not exceed 20 percent of the fund's total financing.

The Norwegian loans will be disbursed gradually until 2035 and must be repaid by 2075.

Brazil and Indonesia have announced contributions of $1 billion each, according to the Norwegian statement -- meaning pledges to the fund so far have reached half the targeted $10 billion in startup capital to be raised from governments within a year.

"There is no time to lose if we are to save the world's tropical forests," the statement quoted Prime Minister Jonas Gahr Store as saying.