Branded Beijing spies in the 1960s, Communist Party leaders are at last tasting success India's communist leaders whose support is key for Sonia Gandhi's Congress party to form a government carry a controversial past: they were branded as agents of China and jailed for sedition in the early 1960s. Jyoti Basu and Harkishan Singh Surjeet - two of the most senior Marxists now taking centre stage - were arrested and thrown into prison for helping the Chinese during the 1962 India-China war. According to government documents, the communists betrayed India, spied for China, engaged in 'hostile propaganda' against the armed forces and systematically obstructed India's war effort on Beijing's instructions. The government also accused communists of being hand-in-glove with 'collaborators' in Calcutta's 35,000-strong ethnic Chinese community. Of the 50-odd leading Marxists reviled and imprisoned for alleged anti-Indian activities, only Mr Basu and Mr Surjeet are still alive. Mr Basu - the most respected communist in India today - was arrested in Calcutta on November 21, 1962, soon after the war broke out for delivering a speech. He was charged under the draconian Defence of India Act for 'anti-state' activities and jailed for 13 months without trial. According to Mr Basu's biographer, he and other communists became victims of wartime jingoism. Other commentators, while criticising the government's crackdown, say that communists invited trouble by doing everything to appease China and denigrate India. Allegiance to China ultimately led to a split in the Communist Party of India - the country's second-oldest political party, founded in 1925. At an historic conclave in 1964, a sizeable section of the communist leadership refused to brand China as the aggressor and parted company with comrades who felt otherwise. The pro-China faction, which insisted that the war had been engineered by India, was christened as the Communist Party of India Marxist (CPI-M). The CPI-M went on to win provincial elections in West Bengal, Kerala and Tripura. It overshadowed the original party which had aligned itself with Moscow. Mr Basu went on to become chief minister of West Bengal from 1977 to 2000 - a national record. And in 1996, he emerged as the unanimous choice of squabbling rightist parties for premier. But CPI-M turned down the offer. In September 2000, Mr Basu voluntarily stepped down as chief minister after anointing a successor - an exception in India where politicians cling to power until they are booted out. Both nearing age 90, Mr Basu and Mr Surjeet find themselves at the end of their careers - yet once again playing a key role, this time in installing Sonia Gandhi's communist-backed coalition government.