San Juan (AFP) - Tens of thousands of water bottles destined for desperate Puerto Ricans after devastating back-to-back hurricanes slammed into the US island territory remain unopened on farmland almost two years later, emergency aid officials confirmed Monday.

Aerial images captured by AFP show a sea of water bottles, packaged into massive bundles, heaped on what appears to be a private estate in the Higuillar neighborhood in Dorado, 25 miles (40 kilometers) west of San Juan.

In some pictures, the ground isn't visible through the piles. In others, broken pallets can be seen among the stacks.

A spokesman for the US Federal Emergency Management Agency (FEMA) confirmed it had provided the water bottles as part of relief efforts for Hurricane Maria, which occurred in September 2017.

The water had expired, and the bottles were assumed to be in the process of disposal and recycling.

The spokesman declined to give further details on how many bottles of water there were, how long they had been on the farm, and why the water had been allowed to expire.

He added that all the issues were "under review by the legal department."

Large sections of Puerto Rico spent months without electricity or water after consecutive hurricanes -- Irma and Maria -- battered the American territory in September 2017, leaving nearly 3,000 dead.

The Puerto Rican government has come under fire for its hurricane recovery efforts, which have largely been viewed as slow and sloppy.

In early July, prosecutors charged six former government officials with embezzling $15 million in hurricane reconstruction money.