Bulgarian state-owned natural gas transmission network operator Bulgartransgaz said that its 351 million levs ($203 million/180 million euro) compressor station construction tender has been suspended over a complaint filed with the competition regulator, asking for the temporary suspension of the procedure. The procedure will remain suspended until the competition regulator dismisses the request for its suspension, or, in case it grants the request, until a final ruling on the complaint is published, Bulgartransgaz said in a statement on Thursday.According to data from the Commission for Protection of Competition's (CPC) website, the complaint was filed by Romania-based piping systems provider J. Christof E&P Services, which objects to clarifications provided by Bulgartransgaz in relation to questions raised by potential participants in the procedure. The clarifications concern various aspects of the procedure, including access to documents, parts of the technical specification, requirements for participation, and others.Earlier this week Bulgartransgaz said that a consortium of local company Klimatronik, Belarus-based construction company Alvora, Ukraine's Poltavaspezmontage and Spanish infrastructure consulting company TEC Cuatro, and another consortium comprising Bulgaria's Glavbolgarstroy and Germany's Ferrostaal Industrieanlagen have placed bids in the tender.