Taiwan opened its office in the Somaliland capital Hargeisa on Monday, in a sign of deepening ties between the two de facto sovereign territories that are denied widespread international recognition.

Democratic and self-ruled Taiwan is officially recognised by only 15 nations since China poached seven of its remaining diplomatic allies after President Tsai Ing-wen came to power in 2016.

Tsai describes Taiwan as “already independent”, but China views the island as its own territory and has vowed to seize it one day, by force if necessary.

Taiwan has for decades been engaged in a diplomatic tug-of-war with Beijing in which each side tries to woo the other’s allies with financial and other incentives.

Chinese foreign ministry spokesman Zhao Lijian told a regular press briefing that Beijing “firmly opposes Taiwan and Somaliland setting up official organisations or conducting official relations with each other”.

“There is only one China in the world and Taiwan is an inseparable part of it,” he said.

Somaliland declared independence from Somalia in 1991 in a move not recognised by the international community.