Beijing claims democratic Taiwan as part of its territory and has never renounced the use of force to bring it under China's control.

Since the 2016 election of President Tsai Ing-wen -- who does not recognise China's claim on Taiwan -- Beijing has stepped up military pressures, sending in warplanes and naval vessels near-daily around the island.

In the 24 hours leading up to 6:00 am Friday (2200 GMT Thursday), the Ministry of National Defence said it also detected six naval ships operating around Taiwan.

The ministry added that among the 36 military aircraft detected, 13 "crossed the median line of the Taiwan Strait", the sensitive waterway separating China from Taiwan.

Friday's announcement comes on the heels of nighttime activity by the Chinese military, with Taiwan's defence ministry announcing around 10:30 pm Thursday that 20 fighter jets, aerial unmanned vehicles and transport planes had been detected from 7:30 pm.

It is also the day after an uptick in activity during the 24-hour period ending at 6:00 am Thursday, when the ministry said Beijing had sent in 32 aircraft.

Relations between both sides of the Taiwan Strait have been frosty since Tsai's election in 2016, with China cutting off high-level communications due to her stance that the island was "already independent" -- a redline for Beijing.

Her deputy Lai Ching-te, who China regards as a "dangerous separatist", was elected in January after warnings from Beijing that he would bring "war and decline" to the island.

Lai and vice president-elect Hsiao Bi-khim of the ruling Democratic Progressive Party (DPP) will take office on May 20.

Hsiao -- who was formerly Taiwan's de facto ambassador to the United States -- has been travelling in recent days, including to the Czech Republic and the European Parliament in Strasbourg, according to photos posted on social media platform X by European politicians.

China's Taiwan Affairs Office on Tuesday slammed Hsiao over her visit to the Czech Republic, saying it served "the purpose of Taiwan independence... and is unhelpful for peace and stability in the Taiwan Strait".

Beijing often reacts to any diplomatic acknowledgement of high-ranking Taiwanese officials, criticising other countries for the merest semblance of acknowledgement of the island's sovereignty

- Chinese boat row -

Adding to tensions, a row between Taipei and Beijing over a fatal fishing boat incident has dragged on since last month.

A Chinese speedboat carrying four people capsized on February 14 near Taiwan's Kinmen islands while being pursued by the Taiwanese coast guard, killing two people while the other two survived.

Beijing has accused Taiwanese authorities of "seeking to evade their responsibilities and hide the truth" about the incident, while a Taiwanese coast guard official has said the boat involved was zigzagging and "lost its balance" before capsizing.

China has said it will step up patrols around Kinmen following a series of deadly incidents, including the sinking of another boat in the area this month that resulted in the deaths of two crew members.

The highest number of warplanes around Taiwan occurred last September when 103 Chinese aircraft were detected in a 24-hour period, according to daily data released by the defence ministry.

Taiwan has criticised China for the increased use of "grey-zone" harassment, tactics that experts say stop short of open warfare but are enough to exhaust Taipei's military.