NEW DELHI? Indian Prime Minister Manmohan Singh flew to Russia on Sunday on a visit to strengthen ties between the two long-time allies and finalize a deal to expand cooperation on nuclear energy.

Singh's two-day trip, his sixth to Russia as prime minister since 2004, was also designed to firm up defense deals that have been hit by delays in delivery, the Press Trust of India (PTI) news agency said.

Singh will hold talks with Russian President Dmitry Medvedev and Prime Minister Vladimir Putin as part of an annual leadership meeting between the two countries which forged a strategic partnership deal in 2000, officials said.

"This is a partnership based on the solid foundation of long-standing friendship, deep mutual trust and strong convergence of interests," Singh said in a statement before leaving.

Singh's visit to Moscow comes after he held talks with US President Barack Obama in Washington last week, focusing on South Asian security and economic links.

Foreign Secretary Nirupama Rao said India and Russia were trying to put together an agreement that would broaden a nuclear fuel import pact.

"Negotiations are at an advanced stage and we hope to sign it during the visit," Rao told reporters Saturday.

The pact would guarantee unhindered supply of uranium for Indian reactors and the right to reprocess spent fuel, PTI quoted unnamed officials as saying.

Russia is already building two nuclear power units in the southern Indian state of Tamil Nadu and has agreed to install four more nuclear reactors there as part of an agreement signed during Medvedev's visit to India last year.

India negotiated an accord with the United States last year which resulted in the removal of a 34-year-old embargo on sales of civilian atomic technology.

It also obtained an exemption from the Nuclear Supplier Group that controls global atomic commerce, allowing it to buy nuclear fuel and power plants to boost its electricity production.

Rao said Singh would try to resolve hiccups over deliveries and pricing of military hardware from Russia, which accounts for 70 percent of Indian defense products.

India's plans to acquire a retired Soviet aircraft carrier five years ago have turned into a headache with Moscow now demanding 1.2 billion dollars in addition to 1.5 billion dollars it sought in 2004 to refit the ageing vessel.

"The matter is under active discussion in an atmosphere of cooperation," Rao said. "We hope to work for a mutually satisfactory solution."