Construction on the middle route of the colossal South-to-North Water Diversion project is accelerating this year, two years ahead of the route's original deadline.

The project, the largest known water diversion project, is designed to take water from the massive Yangtze River in the South to satisfy demand in the North's drought-prone cities via three water-diversion routes.

As part of the middle route, stretching about 1,432 km and affecting Central China's Henan and Hubei provinces, water from the Danjiangkou Dam reservoir in Hubei will be diverted to Beijing.

By June 10, more than 60 percent of the projects along the central route in Henan province - covering 731 km of the total length of the route - had been completed, according to the project administration.

"Projects on the central route are now going into high gear, and they are expected to be finished by the end of 2013 and provide water in 2014," Wang Xiaoping, head of the project office in Henan, said at a working conference on Tuesday.

"Ensuring construction progress and quality are both top concerns," Wang said.

Experts with Wang's office said that the upcoming high temperature and flood season, as well as technology constraints, are great challenges for future construction.

Construction on the eastern route, which began to transfer water from East China's Jiangsu province along the Yangtze River into Shandong province in 2002, will be completed by the end of this year, said Zhang Ye, deputy director of the State Council's office in charge of the project.

"According to the current progress of construction, the eastern route will begin to provide water in 2013 on its original deadline," he said.

Construction of the final west route, which is hampered by difficulties of crossing the 3,000-5,000 meter-high Qinghai-Tibet Plateau, is not yet scheduled to begin, experts said.