India is to build at least ten more nuclear reactors with Russia, Prime Minister Narendra Modi has said after talks with President Vladimir Putin in New Delhi.

"We have outlined an ambitious vision for nuclear energy of at least 10 more reactors," Modi said at a press briefing on Thursday.

Russia's President Vladimir Putin held talks with India's new prime minister as sanctions-hit Moscow seeks to strengthen energy, defence and strategic ties in Asia.

Putin on was looking to advance nuclear power, oil and natural gas and even diamond deals with long-standing ally India, on his first visit since Prime Minister Narendra Modi swept to power in May.

The president is seeking new markets for Russia's natural resources as its economy reels under US and EU sanctions over its backing of an uprising in Ukraine and annexation of Crimea.

"He [Putin] wants to show the world that he isn't isolated and to a certain extent he's not, he still has the BRICS countries," Russia expert Nandan Unnikrishnan said, referring to the emerging economies of Brazil, Russia, India, China, and South Africa.

"India now is all about development and it's looking to Russia to share its technology on military hardware for making here," said Unnikrishnan, a senior fellow with Delhi-based think-tank the Observer Research Foundation.

Putin is expected to focus on boosting two-way trade, which stands at just $10bn a year despite strong ties that date back to the 1950s after the death of Stalin.

Since coming to power, Modi has sought closer ties with US President Barack Obama, who has accepted an invitation to join India's Republic Day celebrations in January.

But India opposes joining Western sanctions against Russia, and is likely to disregard a caution from Washington that now is not the right time to do business with Moscow.

'Unofficial talks'

The acting leader of Crimea, the strategic peninsula that Russia annexed in March, was also holding unofficial talks on Thursday with business leaders in Delhi, a move likely to irk Washington.

Kremlin loyalist Sergei Aksyonov was meeting the business leaders at an upscale hotel, a move aimed at "widening business contacts and deepening economic cooperation" between Crimea and India, a Russian embassy statement said.

Putin said before he arrived early on Thursday that he would be seeking to strengthen their "privileged strategic partnership", singling out more Russian-built reactors for energy-hungry India's nuclear power plants.

Moscow is seeking greater investment from Indian state-run companies in Russian oil and gas projects, including ones being explored in the Arctic.