Chinese embassy said US agencies abroad were doing "disgusting things" to contain China and had showed a "selfish, hypocritical, contemptible, and ugly face"

In its rebuke, China said the statement showed a "sour grapes" attitude by the United States towards "flourishing China-Myanmar relations" and was "another farce on a global tour by the US authorities to shift the attention on domestic problems and seek selfish political gains".

China's embassy in Myanmar on Sunday accused the United States of "outrageously smearing" the country and driving a wedge with its Southeast Asian neighbours over the contested South China Sea and Hong Kong, as tensions mount between the superpowers.

Responding to US claims Beijing was undermining the sovereignty of its neighbours, the Chinese embassy said US agencies abroad were doing "disgusting things" to contain China and had showed a "selfish, hypocritical, contemptible, and ugly face".

The United States last week hardened its position on the South China Sea, saying it would back countries in the region that challenge Beijing's claim to about 90% of the strategic waterway.

In a statement on Saturday, the US embassy in Yangon called China's actions in the South China Sea and Hong Kong, where Beijing has imposed tough new national security laws, part of a "larger pattern to undermine the sovereignty of its neighbours".

The US statement drew parallels between China's actions in the South China Sea and Hong Kong with large-scale Chinese investments projects in Myanmar that the United States warned could become debt-traps, along with trafficking of women from Myanmar to China as brides, and the inflow of drugs from China into Myanmar.

"This is how modern sovereignty is often lost - not through dramatic, overt action, but through a cascade of smaller ones that lead to its slow erosion over time," the US embassy said.

In its rebuke, China said the statement showed a "sour grapes" attitude by the United States towards "flourishing China-Myanmar relations" and was "another farce on a global tour by the US authorities to shift the attention on domestic problems and seek selfish political gains".

"The US should first look in the mirror to see whether it still looks like a major country now," it said.

The Chinese embassy in Yangon did not answer phone calls seeking further comment. The US embassy was not immediately available for comment.

Myanmar has increasingly become a battleground for influence between the two countries since relations between the government led by Nobel laureate Aung San Suu Kyi and the West became strained over its treatment of the Rohingya Muslim minority.

Author and historian Thant Myint-U told Reuters in an email although the country was of negligible economic value to the rivals, its strategic importance as a bridge between mainland China and the Bay of Bengal was hard to ignore.

"Myanmar's instincts since independence in 1948 are to try to be friends with everyone, but it's not clear that's going to remain possible, in this coming period of increasingly febrile superpower rivalry," he said.

"The sheer weight of China's giant industrial revolution next door is already transforming Myanmar; if multi-billion dollar infrastructure projects are added to the mix, the border between the two countries will become increasingly difficult to see," he said.

"It's important to remember that Myanmar was one of the few countries in the world where the last Cold War led to proxy armed fighting which in turn led to military dictatorship and decades of self-imposed isolation."