NEW DELHI: Russian President Dmitry Medvedev clinched agreements Tuesday with Cold War-era ally India to deepen nuclear energy cooperation and develop a supersonic fighter to rival a US stealth jet. Medvedev also threw his weight behind New Delhi's bid to secure a permanent seat on an expanded UN Security Council, following similar calls from Washington and Paris. Leaders from Britain, the United States, France and China – along with Russia, the permanent members of the UN Security Council – have all visited India in the last six months, securing contracts worth a total of around $50 billion. India, the second fastest-growing major economy in the world after China, is one of the top arms importers and plans to spend tens of billions of dollars on defence in the next few years to upgrade its ageing Soviet-era arsenal. Russia and India signed a long-awaited contract to jointly develop a supersonic fifth generation fighter aircraft, invisible to radar like the US F-22 Raptor stealth fighter. They also clinched a deal to expand capacity at a Russian-built nuclear power plant in south India. India's growing ties with the US, underscored by a landmark civil nuclear deal, has made Russia ill at ease. Russia has been India's close economic and political partner since Soviet days, and monopolised India's defense market for decades. Medvedev, accompanied by a large delegation of business leaders, met Prime Minister Manmohan Singh and ruling Congress party chief Sonia Gandhi. On Wednesday, he will visit the Taj Mahal in Agra and India's financial capital Mumbai.