About 1,800 armed police officers and People's Liberation Army (PLA) soldiers were hiking on Sunday toward an expanding "quake lake" in southwest Sichuan Province, hoping to blast away its landslide barrier before it bursts and causes a flood.

"The rescuers have 10 kilograms of dynamite each and are expected to arrive at the site on Sunday night," a PLA spokesman told Xinhua early on Sunday.

Two Xinhua reporters have joined a branch of 150 armed police officers to take a bus from Mianyang Airport to the county seat of Beichuan and then hike to Tangjiashan barrier lake.

The team were about two kilometers from Beichuan county seat at 5 p.m.

Their trekking would be long and hard, with high mountains to climb and potential landslides. "We've found a local guide in Beichuan County who is willing to take us there," said Gong Juncang, an officer. "We tried once before, but couldn't make it to the top after 12 hours."

An afershock measuring 6.4 on the Richter scale at 4:21 p.m. on Sunday, the strongest since the May 12 quake, could still hamper their efforts.

The tremor was felt clearly in Beichuan, where a reporter with the Chinese Central Television said he "could feel the ground and the mountain were shaking."

Earlier attempts by the PLA and armed police to send military helicopters on the same mission were hampered by adverse weather and low visibility at the Tangjiashan lake site in Beichuan.

The local meteorological bureau forecast high winds and thunderstorms for the area on Sunday and Monday.

The Tangjiashan quake lake, which is in danger of bursting as water builds up in it, is one of the more than 30 such lakes in rivers blocked by landslides from the earthquake and thousands of aftershocks.

The lake is 3.2 km upstream from the Beichuan County seat, from which thousands of survivors have been evacuated since Wednesday.

Its barrier is in danger of bursting as the water level rose by nearly 2 meters on Saturday to 723 meters, only 29 meters below the lowest part of the barrier, which measured 752 meters high.

At an emergency meeting in Chengdu, the Sichuan capital, on Sunday, Vice-Premier Hui Liangyu ordered rescuers to remove the risk "with utmost effort and within the shortest possible time."

(Xinhua News Agency May 25, 2008)