ALGIERS, May 25 (Reuters) - Algeria's state energy company Sonatrach launched on Wednesday a pre-qualification bidding round to choose firms that will build six compressor stations at an estimated total cost of $1 billion, according to a Sonatrach document.

The programme is part of a multi-billion dollar expansion of pipelines, compression and pumping stations to be built in the next four years to help the North African OPEC state pump more gas from new fields in the south.

In 2014, Sonatrach short-listed 16 international firms including Bonatti, Techint Group, China Petroleum Pipelines, and Technicas Reunidas.

European and Algerian officials and companies met on Tuesday for a forum to look at ways to overcome bureaucratic and technical problems that have hindered investment in Algeria and to help improve energy cooperation. urn:newsml:reuters.com:*:nL5N18L3AS

(Reporting by Lamine Chikhi; Editing by Patrick Markey and Mark Potter) ((pat.markey@thomsonreuters.com; +213-661-692993; Reuters Messaging: pat.markey.thomsonreuters.com@reuters.net))