BEIJING (Reuters) - Taiwan staff at multinational firms in China have nothing to fear as long as they don't break the law, the Chinese government said on Wednesday, following new legal guidelines that mandate execution in extreme cases for "diehard" separatists.

China, which views Taiwan as its own territory, issued the new guidelines after President Lai Ching-te took office in May, who Beijing has made no secret of disliking and has called a "separatist."

Some foreign companies are considering moving Taiwanese employees out of China, as a result, sources have previously told Reuters.

Speaking at a regular news briefing, Zhu Fenglian, spokesperson for China's Taiwan Affairs Office, reiterated there was no cause for alarm for most Taiwanese, and directly addressed the issue of those working for foreign firms.

"The majority of Taiwan compatriots, including Taiwanese employees working in multinational companies, can be completely at ease in the mainland, as long as they do not engage in criminal acts," she said, referring to the new guidelines.

Taiwan's government raised its travel warning for China after the guidelines were issued, saying people should only go there if absolutely necessary, sparking anger from Beijing.

"Taiwanese people who have visited the mainland know full well there us absolutely no travel risk," Zhu said.

"The Democratic Progressive Party authorities' tactics of intimidating the public cannot bluff or stop them, and will only increase the public's resentment or, and opposition to, the green terror," she added, referring to the colours of Taiwan's ruling party.

China has vowed to go after people it views as Taiwan separatists wherever they may be, although Chinese courts have no jurisdiction in Taiwan or ability to enforce judgements there.

Lai rejects China's sovereignty claims, saying only Taiwan's people can decide their future. He has repeatedly offered talks with Beijing but been rebuffed.