UPDATE 1-E.ON, VNG may sell gas grid EVG Thueringen - sources
* Sale could fetch 300-400 million euros -sources
* EVG operates 1,200 km of grids in Thuringia, Saxony
* Sale may be launched this month or next -source (Adds context on grid sales, background on E.ON)
By Christoph Steitz and Arno Schuetze
FRANKFURT, Feb 5 (Reuters) - German utility E.ON and gas firm VNG AG are considering selling their jointly owned regional gas grid EVG Thueringen in an auction that could fetch 300-400 million euros ($406-540 million), two people familiar with the matter said.
The sale of EVG, which operates a 1,200 kilometre gas grid in the German states of Thuringia and Saxony, could be launched this month or next, one of the people told Reuters.
E.ON and VNG - which is part-owned by EWE AG, Russia's Gazprom and BASF's oil and gas arm Wintershall - both declined to comment.
Power and gas grids have been prime targets for infrastructure investors which are looking to buy into safer assets amid turbulent stock markets and low interest rates.
Late last year, E.ON, Germany's biggest utility, agreed to sell regional gas grid Ferngas Nordbayern GmbH to First State Investments, an asset management business owned by the Commonwealth Bank of Australia.
First State had also led a consortium which acquired the local power distribution grid of Finnish utility Fortum for 2.55 billion euros.
Australian bank Macquarie has also become a major force in European infrastructure M&A, buying RWE's 4,100 kilometre gas network Thyssengas GmbH for an estimated 500 million euros and leading a consortium that won the auction for E.ON's Open Grid Europe gas network in 2012.
E.ON has nearly completed a 20 billion euro asset disposal programme aimed at lowering its 33 billion euro debt pile and streamlining its business, which has come under pressure from record-low wholesale power prices and a boom in rivalling renewable energy sources in its home market.
($1 = 0.7402 euros) (Editing by Maria Sheahan)