A powerful aftershock struck China near the epicenter of the 7.9 earthquake that hit Asia’s biggest country on Monday, Xinhua state news agency reported. As a consequence, Chinese authorities have increased the death toll of the disaster.

The aftershock measured 5.9 on the Richter scale caused massive landslides in Lixian county Friday. The landslides cut off several roads, thus making it harder for rescue crews to reach some parts of the region in order to offer assitence to those suffering after the earthquake.

The chances of finding more survivors under the ruble of the collapsed buildings decreases with every hour and the aftershock that struck China today further hampers the rescue efforts.

As many as 130,000 troops were deployed by the Chinese military to help and several foreign rescue teams are to arrive in China to offer their assistance. Several members of a Japanese professional emergency relief team arrived today in Sichuan, the province worst hit by the tremor, Xinhua reported.

Emergency teams from Russia, South Korea and Singapore are also heading to China.

At least 21,000 people were killed in Sichuan province according to the estimations made by local officials. Authorities expect the death toll to rise to as many as many as 50,000 people.

China’s President Hu Jintao made a trip to Sichuan province Friday morning and urged the rescue teams to make everything humanly possible to find more survivors of the 7.9 magnitude quake.

Nearly 7,000 school buildings collapsed in the earthquake killing numerous children inside them. The Chinese housing ministry has already launched an investigation to find out why the school buildings went down so easily.