* Igor Sechin offers broader cooperation to Japan's business
* Moscow eyes closer ties with Asia, West imposes sanctions (Adds comments on cooperation, details)
TOKYO, March 19 (Reuters) - Igor Sechin, head of Russia's state energy company Rosneft, warned the West on Wednesday that expanding sanctions over Russia's annexation of Ukraine's Crimea region would only make the situation worse.
Visiting Tokyo in a sign that Russia is keen to turn eastwards after incurring the wrath of the West over Crimea, Sechin also offered Japanese investors more cooperation in the development of Russian oil and gas.
Sechin will also visit India, Vietnam and South Korea.
"Looking into expanding sanctions is something that will only make the conflict worse," said Sechin, a long-standing ally of Russian President Vladimir Putin, during a panel discussion at a forum for investment between Japan and Russia.
"It doesn't help solve the problem and is unproductive."
The stand-off over Crimea has caused the most serious East-West crisis since the end of the Cold War, and the United States and the European Union have imposed sanctions on a handful of officials from Russia and Ukraine.
Japanese officials worry any push to impose economic penalties by the West could undermine its drive to improve ties with Moscow, but Sechin, who has likened the sanctions to a blackmail attempt, said Russia was keen to boost investment.
He offered investment possibilities in Russia to Japan, which had threatened to suspend talks on an investment pact and relaxation of visa requirements as part of sanctions over Crimea.
"We offer a substantial expansion of investment possibilities to Japanese investors," said Sechin, who has a history of close ties with Japan.
"We are interested not only in attracting partners to certain projects. We are ready to look into joint investments into all the technological chain: in output, infrastructure, refining and transportation of energy," he said.
Rosneft already has some joint projects with companies from Japan, the world's largest consumer of liquefied natural gas (LNG).
In 2011, when Russia's neighbour stepped up LNG consumption after the disaster at its Fukushima nuclear plant, Sechin, then in charge of energy within the Russian government, personally ordered additional shipments of LNG to Japan. (Reporting by James Topham, Chris Meyers, Tomasz Janowski; additional reporting by Vladimir Soldatkin in Moscow, editing by Elizabeth Piper and Louise Heavens)