Taiwan has unveiled its first domestically-made submarine as it bolsters its defences against a possible Chinese attack.

President Tsai Ing-wen presided over the launch ceremony in the port city of Kaohsiung on Thursday.

US officials have warned that China could be militarily capable of mounting an invasion within the next few years.

Taiwan is a self-governing island which China regards as a renegade province and has vowed to reclaim one day.