India and China have agreed to "disengage as soon as possible" after troops engaged in a series of clashes at their disputed Himalayan border, according to a joint statement from the two countries.

The nuclear-armed neighbours accused each other this week of firing shots across the flashpoint border -- intensifying a months-long standoff that has already claimed at least 20 lives.

Tens of thousands of troops from both sides have been deployed to the border, which sits at an altitude of more than 4,000 metres (13,500 feet).

After a meeting Thursday between Chinese Foreign Minister Wang Yi and his Indian counterpart Subrahmanyam Jaishankar in Moscow, a joint statement said the two sides had agreed to de-escalate.

"(The) border defense forces of both countries should continue dialogue, disengage as soon as possible, maintain the necessary distance, and ease the situation on the ground," the statement said.

The two also agreed to "avoid actions that may escalate the situation".

Throughout the dispute, China and India have issued similar statements calling for restraint and to ease tensions.

The frontier between the two countries has never been properly demarcated.

The countries fought a brief border war in 1962, but officially no shots have been fired in the area since 1975 when four Indian troops were killed in an ambush.