"It is necessary and rational for China to hold military exercises for the sake of national defense," foreign ministry spokesman Liu Jianchao told journalists at a regular briefing.

"We will never allow Taiwan independence and never allow anybody in any form to separate Taiwan from China."

The exercises were to take place in June and July on Dongshan Island in southeastern Fujian province just 150 nautical miles west of Taiwan's Penghu Island, the New Express Daily said, citing a pro-Beijing Hong Kong newspaper.

With China becoming increasingly agitated with independence-leaning Taiwanese President Chen Shui-bian, state press reports called the wargames the first-ever aimed at "striving to control the Taiwan Strait."

The 18,000 soldiers will be deployed from the land, navy and air force of the Nanjing Military Region, where some 500 short-range ballistic missiles are pointed at Taiwan.

"Sukhoi Su-27 fighter jets will be outfitted with KN59M guided air-to-surface missiles in an effort to maintain control over the Taiwan Strait and ensure that tank brigades can make a landing and engage in warfare," the report said.

Submarines, war ships and a guided missile brigade would also be involved in the exercises that were to be led by Lieutenant General Huang Jiang, it said.

Soldiers were deployed on Dongshan Island in mid-May where tanks and armoured personnel carriers had been practicing amphibious landings daily on Jinluan beach, it said.

It was not clear if the full-blown exercises had already begun.

Western diplomats in Beijing played down the drills, saying the number of troops involved was not that large and that the exercises appeared to be routine.

"They are sending a signal by holding the exercises in Fujian, but it is not a provocation due to the size of the exercises," one diplomat told AFP.

According to Hong Kong's Apple Daily, the exercises would be smaller than similar drills held in 2001, when some 100,000 soldiers engaged in amphibious exercises and mock sea warfare aimed at sinking an aircraft carrier.

The Chinese side has taken in consideration the safety of the international shipping lanes in the Taiwan Strait during the games, Liu said, while reiterating that "it is not the first time that China has held such exercises."

Since the re-election of Chen in March, and especially since his inaugural address on May 20, the mainland has racheted up the rhetoric on Taiwan, repeating its long-standing vow to take the island by force should Chen move the territory towards formal independence.

Beijing has considered Taiwan part of its territory awaiting reunification since the end of the civil war in 1949.

Taiwanese defence officials said in April that Taiwan was conducting its own massive military exercises to evaluate the island's defense capabilities against the threat of attack from China.

The seven-month drills, codenamed "Han Kuang (Han Glory) 20", are scheduled to end in November and would test the joint operations of the armed forces.

The United States, Taipei's biggest arms supplier, has repeatedly urged China and Taiwan to refrain from any provocative actions.

Last week, it blasted Beijing in a defense department report for developing a variety of "credible military options" to prevent Taiwan from achieving independence.

In response, Liu Tuesday warned Washington against selling arms to Taiwan.

"We request the United States to fulfill its commitment to the one China policy ... and stop selling weapons to Taiwan in any form, in order not to send the wrong signals to Taiwan separatist forces," Liu said.

WAR.WIRE