RIYADH - Russia is working closely with Saudi Arabia to facilitate bilateral investment in the energy sector and Russian companies are interested in the kingdom's planned new NEOM business zone, energy minister Alexander Novak said on Thursday.

Novak, who was at an investment event in Riyadh held by the two oil producers, said Russian companies were looking at various Saudi sectors such as solar, healthcare, education, artificial intelligence and port infrastructure, according to the Russian energy ministry's Twitter account.

He said that Moscow was working with the Saudi energy ministry to encourage Russian investment in the kingdom's energy sector and vice versa, without giving details.

Last week the chief executive of The Russian Direct Investment Fund (RDIF) told reporters that it plans to participate in building NEOM, a new $500 billion mega-city, in ventures worth several billion dollars in total.

The RDIF and Saudi Arabia's main sovereign wealth fund PIF have already invested $1 billion in nine joint projects, according to Russia's energy ministry.

There are around 25 more projects worth $10 billion under consideration as part of the strategic partnership, the ministry wrote on Twitter, adding that Russian exports to the kingdom have almost doubled this year.

"Cooperation on the 'peaceful atom' could be key," Novak is quoted as saying, referring to nuclear energy. Saudi Arabia plans to award a construction contract for its first two nuclear reactors in 2018.

Novak was part of a Russian delegation including executives from companies such as Gazprom, SIBUR, Lukoil, Sinara, KAMAZ, TMK, United Heavy Machinery Plants, Russian Railways, and Nevsky Machine, according to an RDIF news release.

The trip follows a visit by Saudi King Salman to Russia last month in talks which cemented a relationship that is pivotal for world oil prices and could decide the outcome of the conflict in Syria.

(Reporting by Katie Paul in Riyadh and Vladimir Soldatkin in Moscow, Writing by Sylvia Westall; Editing by Andrew Torchia and Emelia Sithole-Matarise) ((sylvia.westall@thomsonreuters.com; Dubai Newsroom +971 4453 6488; Reuters Messaging: sylvia.westall.thomsonreuters.com@reuters.net))