LUXOR, Egypt (AP) — Authorities have blocked off water purification stations along the Nile in southern Egypt to prevent some 100 tons of diesel oil that leaked from a barge from polluting drinking water, officials said Sunday.

The vessel was docked in Aswan, some 700 miles (1,100 kilometers) south of Cairo, when low water levels caused it to tilt, partially submerge and leak 110 tons of diesel fuel into the Nile on Saturday.

Aswan Governor Mustafa al-Sayed told the MENA news agency that sites along the Nile that feed river water to purification stations have been blocked off as a precautionary measure to prevent polluted water from entering filters.

Egypt gets much of its drinking water from the Nile.

Luxor Governor Samir Farag said the small slick fragmented as it passed through an area of dense grass. Farag said samples of water would be tested regularly as the spill approached Luxor, which is down river from Aswan.

A senior Luxor official, Hussein Ali, said the slick is 60 yards (meters) wide and 1.2 miles (2 kilometers) long, but is shrinking and is not expected to affect water supply stations.

Earlier Saturday, the barge's captain, Yasser Hussein, told police that a drop in water levels caused his vessel to tilt and submerge, allowing the diesel fuel to leak into the river, a security official said.

The official, who spoke on condition of anonymity because he was not authorized to speak to the media, said the barge was unloaded to refloat it.