BRITISH companies were yesterday given another assurance that their investments in China would not suffer because of the deteriorating Sino-British relations over Hong Kong. The deputy director of China's Commission on Economy and Trade, Yu Xiaosong, said the development of Sino-British economic ties depended on whether the British were willing to invest in the mainland. Citing the example of the United States, Mr Yu said: ''Relations between the US and China have been tense in the past few years as a result of their attempts to impose sanctions through the Most Favoured Nation trading status. But American investment in our country is still growing every year.'' Mr Yu, also a member of the economic sub-group of the Preliminary Working Committee (PWC) for the post-1997 government, said the Sino-British deadlock would not affect the economy of Hong Kong. He stressed that the Chinese Government would abide by the Basic Law and try to maintain the stability and prosperity of Hong Kong during the transition. Meanwhile, another PWC member, deputy head of the Public Security Bureau Tian Qiyu, said China would ''immediately'' embark on a scheme to allow mainland-born children of Hong Kong residents to settle in the territory. Mr Tian did not specify the date for the launch of the programme but said the estimated 75,000 children would be allowed to go to Hong Kong in phases. ''It will begin very soon and definitely be conducted in different phases,'' he said.