WASHINGTON (AFP) - The United States voiced hope that India and China will peacefully resolve differences after New Delhi said at least 20 troops died in the Asian powers' deadliest clash in decades.

"Both India and China have expressed a desire to de-escalate, and we support a peaceful resolution of the current situation," a State Department spokesman said.

The spokesman said the US was "closely monitoring" the situation and, referring to India's announcement of casualties, said: "We offer our condolences to their families."

US President Donald Trump last month said he was ready to mediate between India and China, although his administration could not offer further details on what he was proposing.

The State Department spokesman said Mr Trump discussed the situation with China in a June 2 phone call with Indian Prime Minister Narendra Modi.

India is an emerging ally of the US, which has mounting friction with China on multiple fronts.

Ms Alice Wells, then the top State Department official for South Asia, last month said that China was seeking to upset the status quo with India and had to be "resisted".