Paraguay has expelled a visiting Chinese diplomat for allegedly interfering in the South American nation's domestic affairs.

Paraguay's foreign ministry said on Thursday that the envoy's visa was cancelled and the person was given 24 hours to leave.

Paraguay is the only South American country, and one of just 12 worldwide, that has diplomatic relations with Taiwan.

Reuters and other Western media say the diplomat had arrived in Paraguay to attend a UNESCO meeting, but lobbied members of Congress to consider severing ties with Taiwan.

Chinese Foreign Ministry spokesperson Lin Jian said on Friday that Paraguay's accusation was "unfounded and unjustified."

Lin reiterated Beijing's position that Taiwan is an inseparable part of China's territory.

China is using pressure tactics to diplomatically isolate Taiwan, where the administration of President Lai Ching-te does not accept the one-China principle.