Authorities in Taiwan have denied claims printed in a Hong Kong newspaper that its intelligence network in China has been cracked.
Taiwan's president says the report is untrue and politically motivated
The Ming Pao daily reported China had arrested 21 Taiwanese and 15 Chinese nationals in December, describing their arrests as one of Beijing's biggest ever spy ring busts.
A spokesman for Taiwan's presidential office said the report was unfounded.
China's "spy hunt" allegedly began when Taiwan commented on Beijing's weapons.
Taiwanese President Chen Shui-bian revealed the exact number of mainland Chinese ballistic missiles aimed at locations in Taiwan during a campaign rally on 30 November.
But a spokesman for Mr Chen said details of the weapons were freely available on the internet.
"It is public information, not secret intelligence," he said.
"There is no need to send spies to find out there are 496 missiles [aimed at Taiwan].
The information can be found on the web and seen in satellite images."
President Chen said on Monday he may drop his promise not to push for formal independence from China if it aims any more ballistic missiles at Taiwan.
"The Chinese communists refuse to renounce their use of force against Taiwan, as well as continue to raise military spending for arms build-up and deploy more missiles.
"As long as they do this, such moves will be evidence of their attempt to use force against Taiwan," he said.
Taiwan's ministry of national defence and its military intelligence bureau also denied any of their spies have been arrested in China.