Ljubljana - The fish kill that occurred in the stream Glinščica in Ljubljana on Monday is most likely a result of cement milk pollution, as the tests have shown that the cause was not too low a pH or a lack of oxygen in the water.

"The fish kill was not caused by too low water levels, but probably by cement milk being poured into the Glinščica," the local angling club's head Marijan Kerč told the STA on Tuesday after he visited the site together with an inspector for agriculture, forestry, hunting and fisheries.

"Although this is still unofficial information, it's clear that someone was washing the cement milk which then flowed downward into the stream."

The Administration for Civil Protection and Disaster Relief said on Monday that whitish water was coming into the stream from a construction site 100 metres upstream from the fish kill.

The fishermen have already removed the dead fish, mainly chubs (Squalius cephalus), from the stream on Monday, while the veterinary hygiene service took some today.

"There is no more life in this part of the stream," Kerč said, hoping the area will be gradually populated by the fish currently upstream once they need more space.

This is only one of half a dozen fish kills since early June in Slovenia, with all attributed to pollution rather than low water levels amid a serious drought.

The severest fish kill took place in Mali Graben, a canal of the Gradaščica in Ljubljana, where some 1.5 tonnes of fish died at the end of July.

Researchers agreed that the ecological disaster was most likely caused by a chemical spill, although tests did not detect any harmful substances which may have already been washed away by the time the samples were taken.