BEIJING (AFP) - China will spare no effort to ensure a safe Olympics, the foreign ministry said Tuesday, after officials said two alleged terrorist plots from its Muslim-majority northwest had been thwarted.

"I'd like to stress that China is relatively safe, but we will not be careless," foreign ministry spokesman Qin Gang told reporters.

"We will spare no efforts and continue to do a good job in ensuring security during the Olympics. We are confident and competent to ensure that."

Wang Lequan, Communist Party chief in the northwestern Xinjiang region, said Sunday that a January raid on "terrorists," which resulted in the deaths of two militants and 15 arrests, had foiled a planned attack on the August Games.

It was believed to be the first specific threat against this summer's Beijing Olympics to be reported by authorities, although Chinese officials had previously warned that terrorism was the biggest threat to the event.

The alleged plot was the second foiled attack linked to Xinjiang, which has a large Muslim population, to be announced over the weekend.

Passengers on a China Southern Airlines flight attempted to crash a Chinese airliner on Friday flying to Beijing from Urumqi, capital of Xinjiang, an official from the region said on Sunday.

As in the first case, few details have emerged except for a brief statement on Monday from the national aviation authority that passengers on the flight had been carrying "suspicious liquids."

The exiled head of the Uyghur American Association, Rebiya Kadeer, said that China fabricated the alleged plots.

"It's completely untrue. All these allegations are falsified," Kadeer, who joined her US-based husband in 2005 after six years in a Chinese jail, told AFP through an interpreter.

The Xinjiang region of 20 million people is largely populated by ethnic Uighurs and other Muslim minorities, who have traditionally opposed Beijing's rule and clamoured for greater autonomy, which the central government has strongly opposed.