Fifty rivers in the Philippines have been destroyed because people are using them to dump their rubbish, leaving some ecologically dead, an official said Wednesday.

Of the country's 421 major rivers and 20 large river basins, 50 are "highly degraded because of man's abuse and neglect," Environment and Natural Resources Secretary Joselito Atienza said in a statement.

"History tells us that rivers have played an important role in the country's economic growth. Yet, we have disregarded this and continue to dirty our rivers and lakes by turning them into giant septic tanks and trash bins," he added.

One of the ecologically dead rivers is the Pasig which bisects Manila. The government has been relocating thousands of squatters from its banks, but those who remain "continue to throw their domestic waste into the river," he said.

Atienza said 53 percent of the pollution in Philippine rivers is due to domestic waste.

"In the face of climate change, it is important that Filipinos should now adopt water conservation as a way of life," the official said, urging them to plant trees.

"Trees moderate water flows by absorbing large amounts of water during heavy rainfall and releasing it gradually during the dry season.