New Delhi, Dec 10 (PTI): Expansion of ties in a range of crucial sectors like nuclear energy, hydrocarbons and defence will be in focus when Russian President Vladimir Putin and Prime Minister Narendra Modi deliberate at the annual summit here tomorrow with an aim to further strengthen the already close strategic partnership.

In his talks with Modi, both in restricted and delegation level formats, Putin is likely to seek deeper economic engagement with the "time-tested" ally to negate affect of sanctions against Russia by the US and its Western allies over the Ukraine issue.

Both sides are looking at inking 15-20 pacts following the summit which has been taking place since 2000 alternately in Moscow and New Delhi.

Ahead of his visit, Putin termed ties with India as "privileged strategic partnership" and said construction of new nuclear plants besides military and technical cooperation was high on the agenda for talks. He said Russia was keen to export liquefied natural gas (LNG) to India and involve ONGC in oil and gas hunt in the Arctic.

Energy-starved India, which is the third largest oil importer after the US and China -- has been pushing for greater involvement in major gas and oil exploration projects in Russia and both the leaders are set to discuss the issue.

Russia is one of the top oil producers globally and has huge reserves of natural gas.

In the nuclear energy sector, Russia may offer to set up a total of 20-24 nuclear energy production units in India against previously agreed 14-16 plants. Both sides are also likely to come out with a roadmap for cooperation in the overall energy sector.

Russian Ambassador Alexander Kadakin said the two countries will start negotiations for setting up of units five and six at the Kudankulam nuclear power complex soon and may sign a technical pact for units 3 and 4 during Putin's stay here.