PLA Navy ships conduct supply operations at an unspecified location in February 2019. (PHOTO / XINHUA)

The Eastern Theater Command of the Chinese People's Liberation Army has started its combat readiness patrols and exercises around the Taiwan Island, a spokesman of the command said.

Senior Colonel Shi Yi, spokesman for the command, said the operations are a serious warning to the collusion and provocations by "Taiwan independence" separatists and external forces and a necessary move to safeguard China's sovereignty and territorial integrity.

On Friday night, maritime safety authorities in Fujian province published navigational warnings saying that military exercises are scheduled to take place in the coming days in certain areas near the mainland

He said that the operations called "Joint Sword" will take place from Saturday to Monday in the waters and air in the Taiwan Straits and to the north, east and south of the island.

He did not give more information about the exercises.

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On Friday night, maritime safety authorities in Fujian province published navigational warnings saying that military exercises are scheduled to take place in the coming days in certain areas near the mainland.

According to the notices, live-fire drills are scheduled to occur on Saturday, Monday, Tuesday, Thursday as well as April 17 and 20.

It released geographical coordinates of the drill zones, asking ships irrelevant to the event not to enter it.

The military operations are taking place amid the mainland's criticism of the recent provocative "transit" trip of Taiwan leader Tsai Ing-wen through the United States.

Tsai visited countries in Central America from March 29 to April 7, with stops in New York and Los Angeles.

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US Speaker of the House Kevin McCarthy met with Tsai at the Ronald Reagan Presidential Library in California on Wednesday.

In a statement published on Thursday, a spokesperson for China's Ministry of National Defense said China firmly opposes all forms of official interaction between the US and Taiwan and any visit by "leader" of the Taiwan authorities to the US in any name or under whatever pretext.

China also firmly opposes the US side's contact with the ruling Democratic Progressive Party in Taiwan in any form, which violates the one-China principle and the provisions of the three China-US joint communiques.

"The PLA will stand by its responsibility and mission and always stay on high alert. The PLA will resolutely safeguard China's sovereignty and territorial integrity, as well as the peace and stability across the Taiwan Strait," according to the statement.