US Defense Secretary Leon Panetta is due to meet China's leader-in-waiting, Vice President Xi Jinping, during a visit to Beijing this week, officials said Monday.

Xi appeared in public for the first time in two weeks on Saturday after dropping from public view this month, setting off intense speculation about his health and political future.

Panetta was scheduled to hold talks with Xi on Wednesday, the second day of a three-day visit to China, military officials, who spoke condition of anonymity, told reporters travelling with the Pentagon chief.

US officials see the meeting as an encouraging sign and say efforts to build a security dialogue with China are making steady, incremental progress after years of on-again-off-again relations with Beijing's military leaders.

The Chinese government did not confirm Panetta's meeting with Xi until Saturday, the same day the vice president appeared at an event and the day the Pentagon chief departed on his week-long trip to Asia.

Until Saturday, Xi had not been seen in public since September 1 and cancelled meetings with four foreign dignitaries including visiting US Secretary of State Hillary Clinton.

Panetta hosted Xi at the Pentagon in February in an elaborate ceremony usually only conducted for heads of state.

"This basically reflects a continuation of a dialogue that Secretary Panetta began when he hosted the vice president at the Pentagon earlier this year," a senior defence official told reporters.

"So this is an opportunity to not only continue that relationship but also to start looking forward to maintaining ties with what could be future leaders of China," the official said.

Panetta's trip to China was extended an extra day to accommodate the meeting with Xi, officials said.

The Pentagon chief and former CIA director was also due to pay unprecedented visits to an armoured force engineering academy and a naval facility in Qingdao, which is home to the Chinese military's north sea fleet, officials said.

Panetta, the first Pentagon chief to be invited to see the naval station, will get a tour of a Chinese frigate and diesel submarine, officials said.