LEH/NEW DELHI: As the intruding Chinese soldiers refuse to budge from their occupied position in Daulat Beg Oldi(DBO) sector in Ladakh, two Chinese military helicopters have violated Indian airspace at Chumar, several hundred kilometres southeast of Leh, adding to the prevailing tension. The Chinese choppers entered the Indian airspace on April 21 and hovered over the area for quite sometime and returned after dropping some food cans, cigarette packets and notes written in their local language, official sources said today.

The incident happened five days after a platoon-strength contingent of China's People's Liberation Army ( PLA ) had come 10km inside the Indian territory in Burthe in the DBO sector on the night of April 15 and established a tented post there.

Chumar, which is about 300km from Leh, provides another access to Aksai Chin, an area which is under illegal occupation of China, besides from DBO.

After the incursion incident, Indo-Tibetan Border Police, the border guarding force, has beefed up its strength in the area and Army from the nearby location had increased its surveillance.

Last September, Chinese helicopters flew over Chumar with some of its troops even getting onto the ground. The troops destroyed bunkers and old tents of the Indian Army before returning to their own air space. The situation in the DBO sector, meanwhile, continued to remain tense with the PLA personnel, who have come with some dogs and vehicles, refusing to budge from the area.

After the flag meeting on Tuesday, India asked China to revert to the status quo position in Depsang Valley in Ladakh where troops of both countries were in a face-to-face situation after Indian military alleged that Chinese forces intruded nearly 10km inside Indian territory.

Apart from the flag meetings between the local military commanders of the two countries, the issue has also been taken up by the officials of the foreign ministries under a working mechanism that was established to address problems faced by the two armies on the ground while patrolling the vast tracks of disputed boundary.

The incident has thrown out of gear a flurry of engagements at the top between the two countries before the planned visit of Chinese Premier Li Keqiang's visit to New Delhi next month.

Li, who took over from Wen Jiabao last month, chose India to be his first trip abroad as Prime Minister to send a message of friendship as well as importance China attached to improve relations with New Delhi.

From India, Li plans to go to Pakistan, China's all weather ally.

The new Pakistan government, which is expected to be formed after elections next month, is expected to be in place when his visit take place.

