UPDATE 1-Nabucco key to stop states turning east-adviser

* Nabucco hopes Turkmenistan will be a supplier of gas

* Turkey transit will be crucial to EU-backed pipeline

* Other projects not viable for diversification - Fischer

(Adds Nabucco, South Stream comments)

By Sylvia Westall

VIENNA, Jan 26 (Reuters) - Europe must strengthen ties to countries like Turkmenistan and Turkey through the Nabucco gas pipeline to ensure they do not turn to the energy-hungry east instead, a top project adviser said on Wednesday.

Former German Foreign Minister Joschka Fischer, who is an adviser to the 7.9 billion euro ($10.8 billion) plan backed by the European Union, said he was glad the bloc was pushing ahead to open up the so-called Southern Corridor through the project.

"Whether these regions will turn their faces to the east or to the west or two sides in a balanced way...this depends on whether Europe is determined to open up the Southern Corridor.

"We are not only talking about oil and gas supplies, we are also talking about a strategic position of Europe," Fischer told a European gas conference in Vienna.

"If we don't open up the Southern Corridor then Turkmenistan will have no other option but to turn to the east. This will have very serious consequences for Europe."

The Nabucco project, which has faced delays over supply talks, aims to transport up to 31 billion cubic metres (bcm) of gas a year from the Caspian region and Middle East to Europe via Turkey and the Balkans and reduce reliance on Russian supplies.

The project, which aims to transport its first supplies in 2015, gained impetus after the Russia-Ukraine gas row of 2009, which cut around a fifth of Europe's supply in winter.

Turkey is not a supplier but will be an important transit country for the project. Fischer said Nabucco was having a "very positive impact on the relationship between Turkey and Europe."

GAZPROM PLAN "WILL NOT HELP EUROPE"

Analysts say Europe may not be able to sustain all of its proposed gas supply pipelines although it will need to build some soon to ensure supplies later this decade. [ID:nLDE6AE0KR]

Fischer said Nabucco was the only viable way to diversify the region's gas supplies, unlike Gazprom's (GAZP.MM) rival South Stream or smaller projects. He suggested the smaller planned pipelines like the $3.4 billion ITGI or $1.5 billion TAP could be integrated into Nabucco as "one project."

A spokesman for Nabucco said such integration was not a topic of discussion for its shareholders at the moment.

South Stream, which Gazprom argues is easier to realise, aims to transport 63 bcm of gas under the Black Sea via the Balkans.

"(The aim) is to eliminate all the transit risks, including the Ukrainian risks," Valery Yazev, deputy chairman in the State Duma told the conference.

Its critics say it only takes existing Russian gas through a different route and will not diversify supplies.

"This is nothing which will help Europe, this is not part of a diversification strategy, neither in a strategic way nor in a direct way for gas supplies," Fischer said.

Azerbaijan this month committed to providing Europe with gas through the Southern Corridor, whereas talks with Turkmenistan are not as advanced. [ID:nLDE70E07P]

Nabucco's shareholders are Austria's OMV (OMVV.VI), Hungary's MOL MOLB.BU, Romania's Transgaz TGNM.BX, Bulgaria's Bulgargaz, Turkey's Botas and Germany's RWE (RWEG.DE). (Editing by Jason Neely and James Jukwey)