ATHENS (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 )