TAIPEI — South Africa has threatened to close Taiwan’s de facto embassy if it is not relocated, while Mongolia shut down a hotel hosting an annual Taiwan reception, in what experts see as the latest signs of China’s campaign to isolate Taipei internationally.

The South African government told Taiwan to move its representative office out of Pretoria by the end of October, an official from Taiwan’s government said. South Africa made it clear that there was no room to negotiate and that if Taiwan does not comply, the office will be closed, according to the official.