More than 20 Chinese warplanes were detected around Taiwan, with 11 crossing a sensitive median line separating the self-ruled island from China, Taipei's defence ministry said Thursday, the first significant show of force since the weekend's presidential election.

The ministry, which releases data daily on the Chinese military presence around Taiwan, said Thursday that 24 warplanes and 5 ships had been detected in the 24 hours leading up to 6 am (2200 GMT).

"11 of the detected aircraft had crossed the median line of the Taiwan Strait or entered Taiwan's southwest and north (air defence identification zone)," the ministry said in a statement.

Democratic Taiwan has its own government, military and currency -- but China claims it as its territory and has never renounced the use of force to bring it under its control.

Saturday's election was won by the Democratic Progressive Party's Lai Ching-te, who China regards as a "separatist". Beijing warned ahead of voting day that his win would bring "war and decline" to Taiwan.

China -- which maintains a near-daily military presence around Taiwan -- did not send an outsized number of warplanes and naval vessels in the election's immediate aftermath.

But it drew first blood in the political sphere, with Pacific nation Nauru abruptly announcing Monday it would switch diplomatic recognition from Taiwan to China, leaving Taipei with just 12 countries or states that still do.

The largest number of warplanes China has sent during a 24-hour window came in September, when Taiwan detected 103 Chinese aircraft around the island. Forty of them crossed the median line.

The constant stream of Chinese warplanes and naval vessels around Taiwan represents a "grey zone" tactic that stops short of an outright act of war, conflict experts say.