New Delhi: Even as Russia has started delivery of the S-400 Triumf air defence missile to China, negotiations for the sale to India of the multi-barrel system with a range between 40 km and 400 km are at an "advanced stage" and should not be hurried up, a top Russian official has said.

In an interview to IANS, Sergey Chemezov, CEO of Rostec Corporation, which was formed over a decade ago to consolidate strategically important companies, said it is important not to "rush" with the contract, and give both parties time for the negotiations.

"Discussions on this contract are at an advanced stage. Currently, the technical details of the contract are being discussed," said Chemezov of the deal, pitched to be worth Rs. 39,000 crore ($5.5 billion) for "the supply of the most modern equipment for strategic purposes".

"The inter-governmental agreement on this project was signed in Goa just one year ago," Chemezov noted, adding, "It is important not to rush things and give both parties time for negotiations."

The deal was signed during Russian President Vladimir Putin's visit to India in October 2016, and negotiations are being conducted on factors like technology transfer, the final price and training of personnel before the contract is finalised.

Apart from China, the missile system has also been bought by Turkey, which has inked a deal for four S-400 batteries for around $2.5 billion.

Russia has said that several other countries, including nations in West Asia and Southeast Asia, have also evinced interest in the S-400.