Chinese astronauts are capable of conducting medium and long-term space missions and enduring the harsh physical conditions involved, a senior astronaut said on Thursday.

"From Shenzhou V to Shenzhou X, we have been laying the foundation for future medium and long-term missions," said Nie Haisheng, one of three astronauts who took part in last month's 15-day space mission, the longest yet for China.

Nie was speaking at the astronauts' first news conference since the mission aboard the Shenzhou X spacecraft in June. The craft returned to Earth on June 26, and the three spacemen have been kept in quarantine since then, allowing them time to recover.