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By Edward McAllister and Lefteris Papadimas

ATHENS, Nov 6 (Reuters) - U.S. oil giant ExxonMobil ( XOM )

has signed a deal with Energean ( EERGF ) and Helleniq

Energy to explore for natural gas offshore Greece,

the companies said on Thursday.

ExxonMobil ( XOM ) expects first gas from the project in Block 2 in

western Greece in the early 2030s if all goes well, John Ardill,

the company's head of global exploration, told Reuters on the

sidelines of a conference in Athens.

The Exxon project will require an investment between $50

million and $100 million, he said. Exxon will take a 60% stake

in the project and will become operator if test drilling proves

successful.

The deal increases U.S. interest offshore Greece, which last

month named a consortium of U.S. oil major Chevron ( CVX ) and

Helleniq Energy as the preferred bidder for exploration in other

blocks.

Greece produces small volumes of oil and relies on hefty gas

imports for power generation and domestic consumption.

It has been keen to explore for gas and bolster its role as

a transit route as the European Union seeks to phase out Russian

gas imports in the coming years.

(Writing by Angeliki Koutantou )