QUITO (Reuters) - Spanish oil firm Repsol said on Thursday it contained a small crude spill in a block bordering Ecuador's largest rain forest park, which is inhabited by Indian tribes and rare animal species.

Repsol spokesman Federico Cruz said the company had not determined the cause of the spill of 100 barrels of crude that occurred late on Wednesday.

"We know that no river or community has been polluted," Cruz said.

Ecuador's Oil Ministry said in a statement it sent a team of experts to determine if the spill caused damage to the 2.4 million-acre Yasuni park deep in the country's Amazon jungle and home to rare species of pumas and pink dolphins.

The ministry did not say if it planned any action against Repsol.

Ecuador wants rich countries to pay $350 million a year in exchange for it not extracting 1 billion barrels of oil under the Yasuni reserve. Quito says leaving the oil in the ground would protect the environment in the Amazon to the benefit of all countries.

Repeated oil spills caused by old and unprotected pipelines of the state oil firm, Petroecuador, has polluted other nature reserves inside the Amazon in recent years.

(Reporting by Alonso Soto; Editing by Peter Cooney)