Chinese troops have advanced in recent days into disputed territory claimed by India, echoing a similar incursion last year that raised tensions between the two rival giants, official sources said Tuesday.

Chinese troops twice crossed over the border into a remote area of the western Himalayas, with some unfurling a banner that read "this is Chinese territory, go back", an official said on condition of anonymity.

Indian border police noticed the troops on Sunday in an unpopulated area of Ladakh during a patrol of the informal border that separates India and China.

"It was a temporary peaceful face-off with PLA well inside Indian territory," the official told AFP referring to China's People's Liberation Army.

He said troops returned to India's Burtse area in Ladakh on Monday displaying a banner "understood to be saying 'this is Chinese territory, go back'."

Indian army spokesman Colonel S D Goswami declined to confirm if any such incidents had taken place. But the incursions were confirmed by several official sources.

Chinese troops crossed over the border into the same area last April and set up camps, triggering a three-week standoff with Indian soldiers which was only resolved after senior officers from both sides reached an agreement for a joint pullback.

That row had threatened to dent improving ties between the two countries which have long been dogged by mutual suspicion -- a legacy of a 1962 border war.

The informal border separating China and India is known as the Line of Actual Control (LAC). While it has never been formally demarcated, the countries have signed two accords to maintain peace in frontier areas.

Small incursions of a few kilometres (miles) across the contested boundary are common but it is rare for either country to set up camps in disputed territory.