Bulgarian gas transmission system operator Bulgartransgaz said it had opened a tender for an exploratory drilling at Chiren underground gas repository an indicative value of 9.77 million levs ($5.4 million/5.0 million euro).
The value of the contract does not include value added tax (VAT), Bulgartransgaz said on Wednesday on its website.
Bids must be sent by May 25.
Bulgartransgaz is a subsidiary of state-owned Bulgarian Energy Holding.