(Adds Shell Bulgaria and Eco Petroleum comment)
SOFIA, April 22 (Reuters) - Bulgaria's anti-monopolywatchdog said it had raided the offices of Eco Petroleum, partof Hellenic Petroleum, and Shell Bulgaria, owned byRoyal Dutch Shell, in an investigation into possiblecartel agreements.
Bulgarians complain of high fuel costs despite a plunge inglobal oil prices and a call by Prime Minister Boiko Borisov forthe competition authority to speed up checks on the fuel sector.
"Employees of the Commission for Protection of Competitionare carrying out surprise checks on site at the offices of EcoBulgaria and Shell Bulgaria," the commission said in a statementon Friday.
Eco and Shell both confirmed in separate statements thatchecks were being made place at their offices and said they werefully cooperating, but denied any wrongdoing.
"We are confident that Shell Bulgaria operates in accordancewith Shell's corporate values and its business principles forfair and ethical competition and within the framework ofapplicable legislation," the company said in a statement.
Eco Petroleum said the only reason it was included in theprobe was that it is Bulgaria's fourth biggest fuel retailer.
The companies being investigated are all members of theBulgarian Petrol and Gas Association, which has said there areno cartel agreements between any of its members.
The latest raids follow others earlier this month on theBulgarian offices of Russia's Lukoil and Romania'sRompetrol.
In February, the watchdog began investigating the fourcompanies, as well as the offices of OMV, Nis Petrol,controlled by Russia's Gazprom Neft and BulgarianPetrol, over possible price fixing.
It has also launched a probe into the Lukoil NeftochimBurgas oil refinery over possible breaches of competition rulesrelated to the sale of its fuels on the local market. (Reporting by Tsvetelia Tsolova and Angel Krasimirov; Editingby Alexander Smith/Ruth Pitchford)