India on Thursday said it was engaged with China at military and diplomatic levels to resolve the border standoff in eastern Ladakh, but at the same time asserted that the country is "firm" in its resolve to protect its sovereignty and national security.

External Affairs Ministry Spokesperson Anurag Srivastava said India is committed to the objective of maintenance of peace and tranquillity along the Line of Actual Control and that Indian troops take a very responsible approach towards border management.

"The two sides have established mechanisms both at military and diplomatic levels to resolve situations which may arise in border areas peacefully through dialogue and continue to remain engaged through these channels," he said at an online media briefing.

Srivastava's comments came even as both Indian and Chinese troops continued to engage in a tense standoff for over three weeks in Pangong Tso, Galwan Valley, Demchok and Daulat Beg Oldie in eastern Ladakh.

Defence sources said military reinforcements including troops, vehicles and artillery guns were sent to eastern Ladakh by the Indian Army to shore up its presence in the areas where Chinese soldiers were resorting to aggressive posturing.

In a conciliatory tone, Chinese Ambassador Sun Weidong on Wednesday said China and India should never let their differences shadow the overall bilateral ties and adhere to the basic premise that the two countries pose no threat to each other.

"The Indian troops take a very responsible approach towards border management and strictly follow the procedures laid out in various bilateral agreements and protocols with China to resolve any issue that may arise in the border areas," Srivastava said.

"India is committed to the objective of maintenance of peace and tranquillity in the border areas with China and our armed forces scrupulously follow the consensus reached by our leaders and the guidance provided," he said.

The MEA spokesperson's comments appeared a bit conciliatory compared to his remarks last week when he said the Chinese military was hindering normal patrolling by indian troops along the LAC.

On Wednesday, Chinese Foreign Ministry spokesman Zhao Lijian said both China and India have proper mechanisms and communication channels to resolve the issues through dialogue and consultations.

In the media briefing, the MEA spokesperson referred to various bilateral agreements and protocols agreed to by India and China to resolve the border dispute.

Srivastava mentioned about the Agreement on Maintenance of Peace and Tranquillity along the Line of Actual Control in the India-China border areas, 1993 as well as referred to the Agreement on Confidence Building Measures in the Military Field along the LAC which was finalised in 1996.

He also talked about the Protocol on Modalities for the implementation of the Confidence Building Measures in the Military Field along the LAC (2005), the Agreement on the establishment of a working mechanism for consultation and coordination on India-China Border Affairs (2012).

The situation in eastern Ladakh deteriorated after around 250 Chinese and Indian soldiers were engaged in a violent face-off on the evening of May 5 which spilled over to the next day before the two sides agreed to "disengage" following a meeting at the level of local commanders.

Over 100 Indian and Chinese soldiers were injured in the violence.

It is learnt that the Chinese side was particularly peeved at India laying a key road in the Finger area of Pangong Tso Lake besides another road connecting the Darbuk-Shayok-Daulat Beg Oldie road in Galwan Valley.

The incident in Pangong Tso was followed by a similar incident in north Sikkim on May 9.

On May 5, the Indian and the Chinese army personnel clashed with iron rods, sticks, and even resorted to stone-pelting in the Pangong Tso lake area in which soldiers on both sides sustained injuries.

In a separate incident, nearly 150 Indian and Chinese military personnel were engaged in a face-off near Naku La Pass in the Sikkim sector on May 9. At least 10 soldiers from both sides sustained injuries.

The troops of India and China were engaged in a 73-day stand-off in Doklam tri-junction in 2017 which even triggered fears of a war between the two nuclear-armed neighbours.

The India-China border dispute covers the 3,488-km-long LAC. China claims Arunachal Pradesh as part of southern Tibet while India contests it.

Both sides have been asserting that pending the final resolution of the boundary issue, it is necessary to maintain peace and tranquillity in the border areas.