China has warned airlines to avoid flying in the airspace around Taiwan as Beijing steps up military exercises around the island, Bloomberg reported, citing carriers and a Korean transport ministry official.

The warning comes amid US House Speaker Nancy Pelosi's controversial visit to Taiwan. After she landed, China announced it would hold military exercises — including live drills — around Taiwan from Thursday to Sunday, state-run Xinhua News Agency wrote in an announcement authorized by the Chinese defense ministry.

South Korea's Korean Air told Bloomberg it's planning to re-route some flights to South Asia to avoid Taiwanese airspace over the next few days. Hong Kong's Cathay Pacific advised pilots to carry extra fuel in the event they need to reroute. Both airlines did not immediately to Insider's requests for comment.

The announcement of Chinese military exercises and heightened cross-straits tensions led to intense speculation in Taiwan over whether flight disruptions in Taiwan's airports this week are due to the drills.

Wednesday alone saw more than 30 flight cancellations from Taiwan's Taoyuan International Airport. Another 40 flights scheduled for Thursday have also been cancelled, according to Taiwan's United Daily.

The airport played down the speculation, telling the news outlets that the cancellations have nothing to do with China's military exercises and that operations are running normally. Taiwan's borders are still largely closed due to the COVID-19 pandemic.