Astronauts on the upcoming Shenzhou XII mission have undergone intensive training in planned extravehicular activities, commonly known as spacewalks, according to Liu Boming, a member of the crew.

"Compared with the Shenzhou VII mission, extravehicular operations on this coming mission will be much longer and more sophisticated, and I believe that there will be difficulties and challenges," Liu said at a meeting with reporters at the Jiuquan Satellite Launch Center in Inner Mongolia on Wednesday morning, one day before departure.

"So, we've received comprehensive, systematic and stringent training, including how to respond to emergencies and malfunctions," he said, adding that the crew will work to make each extravehicular task a success through cooperation, and with the support of ground control.

Liu took part in the three-day Shenzhou VII spaceflight in September 2008 with Zhai Zhigang and Jing Haipeng. Liu and Zhai conducted the first, and so far the only spacewalk, Chinese astronauts have undertaken.

During the operation, Zhai remained outside the spacecraft for about 15 minutes, while Liu remained half in and half out of the craft for several minutes, as he assisted Zhai.