After moving to China's southeast Fujian province in 2015 to do business, the man, identified by his surname Huang, and his son were "lured" by two Chinese officials he met to "collect confidential national defence documents", said Taiwan High Prosecutors Office's Tainan branch.

The duo "intended to endanger national security, and to jointly develop a network in Taiwan to lure and absorb... active-duty servicemen," prosecutors said in a statement issued late Monday.

The Huangs were charged with violating national security law and the state secrets protection act, while the soldiers were indicted for violating the Criminal Code of the Armed Forces and for corruption.

Accused of enlisting the two soldiers who worked for the air force's air defence and missile division, the father and son had asked them to sign a letter to pledge "allegiance" to Beijing as well as arranging for them to meet Chinese officials abroad, the statement said.

Then together they collected eight items about the Han Kuang exercise -- Taiwan's largest annual wargames which took place two weeks ago -- and "other confidential military documents" to hand over to Chinese officials either in person or by mobile phone, prosecutors said.

China claims self-ruled Taiwan as its territory and has ramped up military and political pressure on the island in recent years as tensions rose.

The two sides have been spying on each other since the end of a civil war between Chinese nationalists and communists in 1949.

The Huangs' case came after Taiwan's defence ministry vowed to bolster its anti-espionage efforts last week following the detention of an army lieutenant colonel who was allegedly collecting intelligence for Beijing.

A number of former high-ranking Taiwanese military officials have in recent years been accused of spying for Beijing.

In March, a retired navy rear admiral and a former lawmaker were charged over an alleged bid to build a spy network for China.