Russia is to build 10 more nuclear reactors in India over the next 20 years. During a business trip to New Delhi, Vladimir Putin signed a deal with Narenda Modi that both leaders described as “ambitious”.

A Russian-built 1,000MW reactor in Kudankulam in south India went into service recently, and three more are due to follow soon. Russia and India grew close in the 1950 and 1960s, with Russia becoming India’s main arms supplier, but New Delhi has become closer to the USA, Japan and Australia in recent years. According to a number of Indian national-security experts, the relationship with Russia cooled due to delays in

Russian arms supplies, defective spare parts and disagreements over cost. Mr Putin is said to be keen to build a strong relationship with India, believing that this could help to compensate for weakening trade, investment and diplomatic ties with the West following the crisis in Ukraine. Indian leaders have never commented — favourably or otherwise — on Russia’s annexation of Crimea and its involvement in eastern Ukraine.

Among 20 documents signed during Mr Putin’s one-day visit to India were several relating to co-operation in the oil and gas sector, including one concerning a joint study for a Russia-India pipeline and another between Russia’s Rosneft and India’s Essar for the supply of Russian oil to Indian refineries over the next 10 years.

During the visit, Mr Modi said that Russia had offered to manufacture helicopters in India for the country’ s air force. He also reminded journalists that his first trip outside New Delhi as Prime Minister was to the Indian aircraft-carrier Vikramaditya, which is a modified Kiev-class Soviet vessel.