Indian Nobel prize-winning economist Amartya Sen has criticised his friend and prime minister, Manmohan Singh, over India’s tightening of bilateral relations with Burma.

Sen, who is widely known for his work on the economics of poverty and welfare, used a lecture on the Centrality of Literacy on Tuesday in New Delhi to tell Singh that “I do not agree with your policy on Burma”.

“In a democratic country like India, I can say this to the Prime Minister,” he said, comparing free speech in India to the unthinkable possibility of addressing Burma’s top brass in the same manner. It follows a visit to India by the derided Burmese junta chief, Than Shwe, which was met by protests across the country.

Much of Sen’s work has focused on social justice; he won the Nobel Prize in 1998 and is a fellow of both Harvard and Cambridge universities. He is known as a social democrat and much of his academic writings break from the economic mantra of pure materialism: his social philosophy strongly highlights the need for democracy and debate as necessary for secure, rational societies.

As he made the comment, fellow economist Manmohan Singh smiled but gave no official response, the Press Trust of India reported.

Sen also commented on the Maoist insurrection in India, comparing them to their Chinese namesake, Mao Tse Tung, but adding that they did not have the same focus on education as their Chinese counterparts.

But the economist trod a more cautious line when he spoke at an event in Bangkok hosted by the UN Economic and Social Commission for Asia and the Pacific (UNESCAP), speaking favourably of the Thai healthcare system which he described as “exceptional in the context of developing countries” – the healthcare system is widely seen as a product of over thrown former prime minister, Thaksin Shinawatra.

Regarding the recent protests in Thailand, he said that “reports that describe a class war between the rich and the poor are an oversimplification of a very complicated problem”.

“The poor are led by the country’s richest person [Thaksin Shinawatra]. There must be more complicated issues than that,” he added. In fact, according to a Forbes index last year, Thaksin is Thailand’s sixteenth richest person, with the top spot awarded to Red Bull drink magnate, Chaleo Yoovidhya.