Indian Prime Minister Manmohan Singh failed Monday to strike a long-delayed nuclear power deal with Russia during talks with President Vladimir Putin that also focused on big arms and energy deals.

Singh is using one of his last major foreign trips as prime minister before 2014 general elections to seek resolutions to lingering issues with two of India's most important regional partners.

The 81-year-old prime minister will leave Russia for China on Tuesday in a bid to forge closer economic relations and ink a pact to ease tension along their disputed border in a remote Himalayan region.

His trip to Moscow was preceded by gruelling behind-the-scenes negotiations on the next phase of a Russian-built nuclear power plant on India's south coast -- one of the current government's signature projects.

Singh said India and Russia enjoyed a "privileged strategic partnership" that enabled the two giants to coordinate their foreign policy views.

Yet he made no mention of an historic deal for the Kudankulam plant that was first signed in 1988 by then Indian prime minister Rajiv Gandhi and former Soviet leader Mikhail Gorbachev.

The collapse of the Soviet Union and Russia's subsequent years of economic mayhem meant that construction of the plant did not begin until 2002.

Work has been nearly completed on the first two units despite local protests that halted progress for six months in 2011-2012.

India now hopes to strike deals for an additional two reactors at the same location as it looks to meet surging electricity demand.

But the 2010 Fukushima nuclear power plant accident prompted India to adopt a strict new safety liability law that Russia believes should not be applied to this project since it was conceived in Soviet times.

Negotiations about how the dispute can be skirted in time for Singh's meeting with Putin went down to the wire, and failed, despite optimism from India's outgoing government head.

The two sides instead issued a joint statement saying they had "agreed to speed up work on drafting a general framework agreement" on the third and fourth blocks at Kudankulam.

Putin and Singh also took a veiled swipe at Pakistan for its conflicted relations with the Taliban movement that is making its presence felt more prominently in Afghanistan amid the United States' ongoing drawdown of troops.

"Nations that aid terrorists by abetting and protecting them are guilty of committing the acts of terror to the same extent as the criminals who actually perpetrate these crimes," the two leaders' joint statement said.

Russia has been India's biggest weapons supplier for decades and arms talks are always a component of the annual round of meetings between the Indian prime minister and the Russian head of state.

Moscow news reports said the sides were closing in on an agreement for Russia to upgrade four existing Indian diesel-electric submarines and lease out several more.

A Russian military source told the state-run RIA Novosti news agency that New Delhi was also interested in financing the construction of a nuclear-powered submarine that could be delivered to India in the years to come.

"Joint (military) projects confirm the high level of our technical and industrial cooperation," Putin said after the talks.

Singh and Putin said in a separate statement that they intended to "study the possibility" of Russia sending petroleum products to India by rail for the first time.