Russia plans to deliver the S-400 surface-to-air missile systems to India as per schedule, President Vladimir Putin has said, amidst warnings from the US against the deal.

India announced its intention to acquire S-400 'Triumf' surface-to-air missile systems in 2015. The contract worth USD 5.43 billion was signed during the visit of President Putin to India last year.

"When it comes to S-400 deliveries, everything goes according to plan," President Putin told reporters on Thursday on the sidelines of the just-concluded BRICS Summit here in the Brazilian capital.

"Indian colleague (Indian Prime Minister Narendra Modi) did not ask to to speed up anything, as everything goes well," Putin was quoted as saying by the official Tass news agency.

Prime Minister Modi and President Putin held a bilateral meeting on the margins of the BRICS Summit on Wednesday and they reviewed the progress made in the bilateral ties and discussed ways to further bolster the special strategic partnership.

The US has opposed the S-400 deal with Russia with the Trump administration threatening to impose sanctions on the states that are acquiring weapons and military hardware from Russia.

Senior US officials have cautioned India that the S-400 deal could attract sanctions under the Countering America's Adversaries Through Sanctions Act (CAATSA) law that restricts defence purchases from Russia, Iran and North Korea.

India acquiring the S-400 missile defence system from Russia is a "problem" for the US, Admiral Philip Davidson, who is Commander of Indo-Pacific Command, said in July.

However, India has told the US that it does not intend to give up the deal for the purchase of Russian-made S-400 air defence missile systems.

In June, External Affairs Minister S Jaishankar told his American counterpart Mike Pompeo in New Delhi that India will go by its national interest while dealing with other countries.

The S-400 is the most advanced long-range air defense missile system that went into service in Russia in 2007. It is designed to destroy aircraft, cruise and ballistic missiles, including medium-range missiles, and can also be used against ground installations.

The S-400 can engage targets at a distance of 400 km and at an altitude of up to 30 km.