China and Burkina Faso formally established diplomatic relations on Saturday, after the West African nation severed ties with self-ruled Taiwan, in another victory for Beijing as it keeps up the pressure on Taipei.

The deal was signed by the Chinese government’s top diplomat, State Councillor Wang Yi, and Burkina Faso Foreign Minister Alpha Barry at a state guest house in Beijing in front of reporters.

Taiwan now has only one diplomatic ally left in Africa – the kingdom of Swaziland - and formal relations with just 18 countries worldwide, many of them poor nations in Central America and the Pacific such as Belize and Nauru.

Taiwan is China’s most sensitive territorial issue.

Taiwan has accused China of luring its friends away with offers of generous aid packages. China denies this, and says Taiwan is a part of China with no right to formal diplomatic ties with any other country.

China’s hostility to Taiwan has grown since President Tsai Ing-wen’s election in 2016, as Beijing fears she wishes to push for the island’s formal independence, a red line for China. She says she wants to maintain the status quo.