British Prime Minister David Cameron delivered a speech on the UK's relations with the EU last month, in which he promised an in-or-out referendum on the EU if the Conservatives win the next election.

Although the EU is not willing to see the disengagement of its third biggest economy, just after Germany and France, it doesn't want to endlessly bend to the UK, which interrupts European integration by frequently invoking the escape clause. Germany and France warned the UK not to expect to freely select the rules it wants. And the European media thinks that if the UK leaves, it will be impossible for it to enjoy preferential trade as Norway and Switzerland do. 

Undoubtedly, the UK will benefit from disengagement from the EU in the short run. For example, the UK can save the $12.5 billion that it has to annually contribute to EU finances. But in the long term, the UK will find it hard to play an important role in European and world affairs without EU support.

Of course, even if the Conservatives win the next election, the referendum cannot be held until 2017. It's still uncertain whether the UK will break from the EU, but we have to consider the possible effects on China.

China supports European unity and wishes to see Europe promote the development of multipolarization, yet a UK exit would be a major setback of European integration, which will surely affect China's European policy.

Economic and trade relations between China and the UK would also be influenced. The UK is a significant trade partner of China. In recent years, thanks to the euro crisis, the import demand from EU nations has slumped and protectionism has intensified, but China-UK trade has still developed steadily.

Due to the UK's economic advantages and loose policy toward Chinese investment, Chinese investment in the UK enjoys fast growth. Besides, the UK is an important source of investment in China, since it is the second largest EU direct investor in China. Lately, the UK also became the first G7 nation to reach a currency-swap agreement with China.

Obviously, China-UK economic and trade relations flourish thanks to the background of British EU membership. Given the possibility of the UK's disengagement, the EU may compress the space for the UK's economy and trade.

Governor of the Bank of France Christian Noyer has argued that it was unreasonable for London to remain the financial center of the eurozone. If this happens, China-UK trade cannot stay unaffected. China should be prepared in case the UK does leave.

The author is the deputy secretary general of the Shanghai Institute for European Studies. opinion@globaltimes.com.cn