In a massive escalation of border tension, an Indian Army officer and two soldiers were killed during a violent confrontation with Chinese troops in the sensitive Galwan Valley in eastern Ladakh on Monday night, the Army said.

It is perhaps the first such incident along the border with China that Indian armed forces personnel have been killed after a gap of nearly 45 years. Four Indian soldiers had lost their lives in an ambush at Tulung La in Arunachal Pradesh in 1975.

The Army said there were casualties on the Chinese side as well but the extent of it was not immediately clear.

Official sources said there was no firing between the two sides.

'During the de-escalation process underway in the Galwan Valley, a violent face-off took place on Monday night with casualties. The loss of lives on the Indian side includes an officer and two soldiers,' the Army said in a brief statement.

A large number of Indian and Chinese troops were engaged in an eyeball-to-eyeball situation in Galwan Valley and certain other areas of eastern Ladakh for the last five weeks.

The incident comes days after Indian Army Chief Gen MM Naravane said both sides have begun disengaging from the Galwan Valley.

The Indian and Chinese armies are engaged in a standoff in Pangong Tso, Galwan Valley, Demchok and Daulat Beg Oldie in eastern Ladakh.

A sizeable number of Chinese Army personnel even transgressed into the Indian side of the de-facto border in several areas including Pangong Tso.

The Indian Army has been fiercely objecting to the transgressions, and demanded their immediate withdrawal for restoration of peace and tranquillity in the area. Both sides held a series of talks in the last few days to resolve the row.