The consortium behind the Nabucco pipeline launched the initial tender process for pipeline materials, Reuters said on April 23, quoting company officials."(This) is a substantial step towards starting construction at the end of 2011," managing director Reinhard Mitschek was quoting as saying. The deadline for submitting bids in the 3.5 billion euro is May 17.Nabucco, which plans to transport 31 billion cubic metres of gas from the Caspian Sea to Austria, is the European Union and US-backed pipeline meant to offer diversification of gas sources for European countries affected by the two stand-offs between Moscow and Kiev, which resulted in interrupted deliveries in January 2006 and January 2009.Government officials from Austria, Bulgaria, Hungary, Romania and Turkey signed the agreement to set up the foundations for the pipeline in July 2009. Since then, the consortium has moved fast to meet its 2014 deadline for starting operations. Construction is scheduled to begin in 2011 and cost 7.9 billion euro.Its main rival is the joint venture between Russia's Gazprom and Italy's Eni, which would take Russian gas under the Black Sea and through South-Eastern Europe, bypassing Ukraine. More expensive than Nabucco, it has double the planned capacity, but remains at the feasibility studies stage.Its main advantage over Nabucco is that it has supply contracts secured, but could find it difficult to sell out its full capacity. Nabucco is still struggling to secure gas for the pipeline, but consortium officials have said that the issue would be solved by the time the pipeline is scheduled to begin pumping gas.