Taiwan’s defence ministry on Monday urged China to stop “destructive, unilateral action” after reporting a sharp rise in Chinese military activities near the island, warning such behaviour could lead to a sharp increase in tensions.

China, which views democratically governed Taiwan as its own territory, has in recent years regularly carried out military drills around the island as it seeks to assert its sovereignty claims and pressure Taipei.

The ministry said that since Sunday it had spotted 103 Chinese military aircraft over the sea, a number it called a “recent high”.

Its map of Chinese activities over the past 24 hours showed fighter jets crossing the median line of the Taiwan Strait, which had served as an unofficial barrier between the two sides until China began regularly crossing it a year ago.

Other aircraft flew south of Taiwan through the Bashi Channel, which separates the island from the Philippines.

China’s activities over the past day have caused “serious challenges” to security in the strait and regionally, the ministry said in an accompanying statement.

Peace and stability in the Taiwan Strait are the common responsibilities of all parties in the region, it added.

“The continuous military harassment by the Communist military can easily lead to a sharp increase in tensions and worsen regional security,” the ministry said. “We call on the Beijing authorities to take responsibility and immediately stop such destructive unilateral actions.”

China’s defence ministry did not immediately respond to a request for comment.

In addition to the air force incursion near Taiwan over the weekend, China last week also dispatched more than 100 naval ships for exercises in the region, including in the strategic waters in the South China Sea and off Taiwan’s northeastern coast, a regional security official told Reuters.

The official, who declined to be named because of the sensitivity of the matter, said the activity put pressure on everyone in the region and called the scale of naval exercises the “largest in years”.

Taiwan’s defence ministry noted last week that July to September is traditionally the busiest season for Chinese military drills along the coast.

China is bolstering its air power facing Taiwan, with a permanent deployment of new fighters and drones at expanded air bases, Taiwan’s defence ministry said in its biennial report this month.