NEW DELHI: In what could turn into yet another mega defence deal with Russia , bilateral negotiations have gained momentum for India's acquisition of four more stealth frigates for around $4 billion.Even as the high-level India-Russia Military Technical Cooperation Working Group (MTC-WG) kicked off its two-day meeting in New Delhi on Wednesday, defence ministry sources said Moscow has submitted "a techno-commercial proposal" for the four multi-purpose frigates packed with sensors and weapons, including the BrahMos supersonic cruise missiles."Under the proposal, two of the frigates will come from Russia , while the other two will be constructed in India. The MoD has asked for some clarifications before taking a decision on the price and inter-governmental agreement," said a source.The MTC-WG also discussed other pending mega defence projects like the joint development of the fifth-generation fighter aircraft and Kamov Ka-226T light utility helicopters as well as the Rs 39,000 crore purchase of five S-400 Triumf advanced air defence missile systems, as was reported by TOI on Wednesday.Russia has apparently dovetailed the frigate project - which was first offered by Russian President Vladimir Putin to PM Narendra Modi over a year ago - with India's aim to lease a second nuclear-powered submarine for around $1.5 billion.The first nuclear-powered Akula-II submarine INS Chakra - being operated by India since April 2012 after paying $900 million - had also been linked to the bigger $2.33 billion deal for aircraft carrier INS Vikramaditya If the deal for the four new 4,000-tonne frigates is indeed inked, they will add to the six Russian stealth frigates already inducted by India. First, three Talwar-class frigates were inducted from Russia in 2003-2004.They were then followed in 2011-2013 by three Teg-class frigates under a $1.15 billion contract inked in 2006. India is quite satisfied with the Teg-class frigates, which have an operating range of 4,500 nautical miles and can handle threats in all three dimensions - air, surface and underwater.But a major problem with the new upgraded Teg or Grigorovich-class frigates on offer is that the warships - lying half-constructed at the Yantar Shipyard in Russia due to a cash-crunch - will need Zorya gas-turbine engines from Ukraine "Ukraine has refused to supply power plants to Russia because of their continuing bilateral problems. But India can directly acquire the engines from Ukraine," said a source.India, of course, has begun to construct its own stealth warships, having inducted three 6,100-tonne Shivalik-class frigates. Another Rs 50,000 crore contract for construction of the seven 'Project-17A' stealth frigates - four at Mazagon Docks at Mumbai and three in GRSE at Kolkata - was inked in February 2015.The Navy currently has around 130 warships as well as 235 aircraft and helicopters. Moreover, the seven P-17A frigates are among the 39 warships and six Scorpene submarines under construction in Indian shipyards for over Rs 3 lakh crore.But India is now eyeing the Russian frigates since it plans a 212-warship Navy by 2027 to ensure effective safeguarding of its huge geostrategic interests from Persian Gulf to Malacca Strait and beyond.