Russian energy giant Rosneft and US group Exxon Mobil struck a $1 billion deal Thursday to hunt for oil under the Black Sea, and promised more joint ventures to come.

Rosneft president Eduard Yurevitch Khudaynatov said he hopes to find a billion tonnes of oil and gas -- mainly oil -- in the 11,200-square-kilometre (4,320 square mile) Tuapse Trough, in waters off the Krasnodar region.

Using the US giant's latest exploration technology, now shared with its Russian partner, the joint venture will survey the seabed this year and hopes the first offshore platform may be operational by the end of 2012, he said.

"It is not just the Black Sea, we will go on together to work on other offshore projects in other areas," he told AFP after the signing ceremony, adding: "But we have a lot of work to do."

Exxon Mobil Development Company president Neil Duffin signed the deal with Khudaynatov at the World Economic Forum in Davos in the presence of Deputy Russian Prime Minister Igor Sechin and Exxon chief executive Rex Tillerson.

Tillerson said ExxonMobil would invest a billion dollars (730 million euros) in the exploration stage of the venture, and that the companies would decide on future investments when the time came to begin production.

Khudaynatov said Rosneft would take 66 percent of eventual production, and Exxon Mobil 33 percent, and vowed that the firms would go on to develop more offshore projects together in other regions.

Sechin played up the political element of the deal, which follows another contract to jointly develop an Arctic field with Britain's BP, stressing that it shows that Russia is open to foreign investment in oil and gas.

"I welcome here our American friends. Thank you and I wish you success," he declared, adding that around 20 percent of Russia's vast hydrocarbon sector was now in the hands of international investors.

"Exxon Mobil technologies will effectively complement Rosneft's experience and resources. Development of this area will beome the springboard for full Black Sea basin development," Sechin said.