The news that US company Chevron hopes to find major shale gas deposits in northeastern Bulgaria have raised the doubts of some experts and the concerns of environmentalists.

Saturday it was announced that Chevron has landed a Bulgarian shale gas exploration concession with a whopping offer of EUR 30 M.

According to the estimates of the bidders, the deposit near Novi Pazar contains between 300 billion and 1 trillion cubic meters of shale gas.

The deal was strongly welcomed by Bulgarian Minister of Economy and Energy Traicho Traikov. In the past, US ambassador to Bulgaria James Warlick has spoken in support of Chevron's interest to prospect in Bulgaria.

Environmentalists however recalled that the technology of extracting shale gas is new and not completely reliable, having caused significant ecological damage in some sites in the USA, where it is already used.

"The technology allows that chemicals pressed into the ground in a process known as hydraulic fracturing could contaminate the underground waters," stated Petko Kovachevo of the Zelenite party for Vsekiden.com.

He recalled that not only chemicals, but natural gas itself might get into drinking water, ruining agriculture and living conditions, as well as that the prospecting area is located in Dobrudzha, a region with traditionally strong agriculture.

On his part, Vasil Filipov, former CEO of Bulgargaz expressed doubts that the deposits of shale gas in the area are as large as the quoted figures, and recommended that Bulgaria orients itself to diversifying its imports.

Valentin Kanev, chair of the Black Sea Oil and Gas Association, offered a more balanced assessment, saying that the technology of shale gas extraction is continuously perfected in terms of safety, and that the very fact that Chevron intends to prospect for gas in Bulgaria is promising.