US House Speaker Nancy Pelosi is expected to stop over in Taiwan in the greatest test of Chinese and American resolve in more than three decades.

Pelosi, who is second in the line of succession to the presidency, is on a tour through Asia, with Singapore, Malaysia, South Korea and Japan on the itinerary.

A senior Taiwanese government official says Ms Pelosi will spend a night in Taiwan, despite warnings of retaliation from China.

A US official says the Defence Department is monitoring Chinese movements in the region and is making plans to keep Ms Pelosi safe.

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