AFP/Moscow

Russian President Vladimir Putin on Thursday hosted Indian Prime Minister Narendra Modi in a visit that could see billions of dollars clinched in defence and energy deals.

Modi arrived in Moscow on Wednesday but the visit officially kicks off Thursday afternoon and includes talks with Putin, a meeting with Russian business leaders and an address at an embassy event celebrating cultural ties.

The two leaders met Wednesday evening for a one-on-one dinner chat that was closed to press and held in the company of only their translators, Kremlin spokesman Dmitry Peskov said, calling it "very constructive and warm."

He added that the Kremlin expected Putin and Modi to ease some visa requirements and oversee the signing of agreements by Russia's state nuclear corporation Rosatom and railway monopoly Russian Railways, without giving details.

Modi said on Twitter that conversation focused on India-Russia ties, calling it "fruitful" and also publishing pictures of the pair exchanging gifts.

Ahead of the trip, Modi said he aims to "deepen the cooperation between India and Russia in the economic, energy and security spheres" and called Russia "one of India's most valued friends in the world."

Officials declined to discuss possible defence deals to be signed in Moscow, though media reports indicated there could be as much as $7 billion worth of contracts agreed Thursday.

- S-400 deal close? -

A report last week said that India's top acquisition body had cleared the purchase of Russia's most advanced S-400 air defence systems.

India was the erstwhile Soviet Union's closest military ally during the Cold War and a major importer of its military hardware.

Dipankar Banerjee, a defence analyst at New Delhi-based think-tank Forum for Strategic Initiatives, said India was "vulnerable to Pakistan and China both in terms of missile attacks and air strikes" and that the defence systems were "very desirable" despite a hefty price tag.

Indian firm Reliance Defence Limited said Thursday it had decided to work with the manufacturer of the S-400 "on the entire range of Air Defence Missile and Radar Systems" that India needs.

It was not clear whether the two companies are ready to reach a firm deal on the missiles.

Russian daily Kommersant this week said Putin's one-on-one talks with Modi would likely be the defining moment for the deal as the two seek to resolve price disagreements.

India could be in the market for as many as five systems, the paper's defence sources said, with deals on Russian frigates and a helicopter-building joint venture also on the cards.

They could announce also the location of a new Russian nuclear plant in the southern Indian state of Andhra Pradesh, an extension of the Russian nuclear plant under construction in Kudankulam where one reactor is already in operation.

Modi is seeking to expand the country's nuclear energy use to meet the rising energy needs of the coal-dependent nation amid global warming risks, with a programme for at least 12 new reactors.

"Energy is a sphere where we can do much more," the Indian premier said in an interview to TASS agency this week.

The trip is Modi's first state visit to Russia since he became prime minister, but the he and Putin have met several times at international events, even discussing the merits of yoga at the BRICS summit in the Russian city of Ufa in July.