Urich Schmocker, head of an International Atomic Energy Agency mission to Spain, said building a central storage facility was just an interim solution.
"Both knowledge in the waste area and the reach for a solution justify a more proactive approach to the final disposal problem," Schmocker said in Seville, southern Spain.
Spain has a storage facility for low- and medium-level waste at El Cabril, near the southern city of Cordoba. No high-level site has been found, but options under consideration include storage deep underground.
Schmocker, of the Swiss nuclear inspectorate, headed a 21-member team to review Spain's Nuclear Safety Commission (CSN) from January 28 to February 8.
The mission made 26 suggestions and two recommendations in the area of security, one of them concerning nuclear waste disposal.
"This is an excellent result," Schmocker said.
Spain's eight aging nuclear power stations face an uncertain future, as operating licenses for seven of them are due for review between 2009-11.
That is within the mandate of Spain's Socialist government, which has vowed to phase out nuclear power amidst a boom in renewable energy sources.
Industry Minister Miguel Sebastian has said, however, that permits could be renewed if operators invested enough in safety.
The government is considering sanctions against the 1,000 MW Asco I plant over what the CSN said was improper handling of a radioactive leak that took place in November last year but was not made public until April.
As part of a bid to cut greenhouse gas emissions and reduce its heavy dependence on imported fuel, Spain has encouraged renewable energy and is now the world's third-largest producer of wind power, with a capacity of 16,000 megawatts.
Spain is now also the world's third producer of solar, and may have up to 1,800 MW by the end of the year.
Overall, nuclear plants have much less capacity than wind and solar plants, at 7,700 MW, yet they usually provide a bigger share of the country's electricity as they work more steadily.