Only China and India can put pressure on the Myanmar junta which recently awarded punishment to pro-democratic leader Aung San Suu Kyi and an American John Yettaw, say experts.
The two countries invest millions of dollars in Myanmar, says a report in New York Times, and vie with each other for strategic influence, so a campaign of co-ordinated action has to focus on the Asian giants.
China remains a major supplier of arms to the regime and India has previously sold them weapons and equipment.
"India and China are crucial," said David Mathieson, from Human Rights Watch. "In addition to the trade, China is the main political protector of Burma. India, meanwhile, is quite happy to go on being the silent partner."
A court in army-ruled Myanmar Suu Kyi guilty of violating an internal security law and sentenced her to three years in prison with hard labour, but it was swiftly commuted to 18 months of house arrest by the country's military.
China is Myanmar's most important trading partner. It invests hundreds of millions of dollars each year in everything from oil and gas to roads and jade and timber extraction.
India is Burma's fourth largest trading partner, behind China, Thailand and Singapore, but that could change as Delhi seeks to counter the mounting influence of Beijing. Along with China and South Korea, India is also a major investor in Burma's Sittwe gas fields, a project that will see the construction of a gas pipeline to China, the report said.
