Indian Air Force helicopters were put on standby for evacuation of affected people in Himachal Pradesh in the event of flash floods as China informed India of the "potentially serious" situation with water flowing over a dam in Tibet.

"The dam has not burst. The water is discharging. But naturally the condition is not stable," External affairs Ministry spokesman Navtej Sarna told reporters in Delhi.

He said the Chinese side has informed New Delhi that water from the aritificial dam has been flowing over it. "They (Chinese) pointed to the instability of the artificial dam and the potentially serious situation that prevails."

On reports that there has been an explosion at the dam, he said there was no confirmation "either way".

Also Read Water released from Tibet lake, alert in HP

Detailing steps taken by the Government, he said IAF helicopters have been put on standby for any evacuation of people and for ferrying supplies as may be required.

A chain of wireless sets have been set up along the villages on the banks of the Pareechu river, Spiti downstream Sutlej downstream of Khad. These would help pass on warning signals of rising water levels.

"All the villages have been sensitised in advance and they have been advised to select places to which people can evacuate in case of flash floods and have been advised to move to the designated places," he said.

Sarna said essential commodities have been stored by the state government at convenient places and river valley projects on these rivers have been warned in advance.
   
An Indo-Tibetan Border Police post has been set up at the point where the Pareechu river enters Indian territory, he said.

A mock drill was carried out by the defence forces and the government agencies on Sunday.

Asked whether any request has been made to the Chinese government for an aerial survey, the spokesman said he was not aware of it.

"The fact is that the situation there is not stable. It is potentially serious. Water is flowing over the dam," he said.

He said heavy rainfall and landslides made access to the artificial dam area extremely difficult.

Observing that the Chinese side have been sharing information with India relating to the prevailing situation, he said, "Both sides have been in close touch."

Asked about the delay in Beijing giving clearance to a four-member Indian technical team to visit the site, he said the area was not easy to access in view of landslides and heavy rainfall.