An agreement on a Japanese-Russian liquefied natural gas project has been delayed after Russia's Gazprom (GAZP.RS) chief canceled a scheduled trip to Japan, raising speculation that a recent territorial spat is casting a pall over bilateral relations, The Nikkei reported in its Thursday morning edition.

The project to build an LNG plant in the far eastern Russian city of
Vladivostok has been planned by the Japanese government and Gazprom , Russia 's state-owned gas company.

The project is considered a pillar of energy-related cooperation between the two nations along with oil and gas development projects off the coast of
Sakhalin . When completed, 5 million tons of LNG is expected to be exported to Japan from the plant. From Japan , the Ministry of Economy, Trade and Industry, Itochu Corp. (8001.TO) and others are expected to handle the facility side of the project.

After reaching a basic agreement in July on the construction of the LNG plant, the Japanese government and Gazprom were to sign this weekend a pact to carry out feasibility studies and to flesh out the details of the project.

Gazprom Chief Executive Alexey Miller was due to visit
Japan , along with Russian President Dmitry Medvedev, who is attending a summit meeting of the Asia-Pacific Economic Cooperation in Yokohama on Saturday and Sunday.

"Something else came up," a Gazprom official handling negotiations said, adding that "there is no problem with the agreement itself."

But some in
Japan see Miller's no-show as a sign of cooling ties between Japan and Russia , following a row over the Russian president's visit to a disputed island off Hokkaido .

Meanwhile, Miller was in
South Korea on Wednesday, accompanying Medvedev, who was attending a Group of 20 meeting. During the visit, Miller announced plans to export at least 10 billion cubic meters of natural gas to South Korea starting in 2017, which some see as a swipe at Japan.

METI, which has been leading the negotiations on the Japanese side, does not expect any major fallout from the cancellation of Miller's visit. But it believes that "an official agreement on the framework will be delayed by several weeks."

For now, METI officials are scheduled to meet the stand-in for Miller in
Japan as early as Friday to exchange opinions on how to proceed from here.