HONG KONG (BLOOMBERG) - China announced an expansion of the Qianhai economic cooperation zone in Shenzhen on the same day as a visit of Hong Kong Chief Executive Carrie Lam to the border city.

The Qianhai zone, which was opened in 2010, will increase in area by around eight times, to around 120 sq km, from roughly 15 sq km currently, according to a document published by the official Xinhua News Agency on Monday (Sept 6).

The expansion is part of a plan to further integrate Hong Kong and Macau's economies into the Greater Bay Area, which includes Guangzhou, Shenzhen and other Pearl River Delta cities.

The plan, which was shy on details, calls for the zone to further open up the financial sector and liberalise the service trade, including supporting more cross-border securities investment, experimenting with links to Hong Kong's financial market, allowing cross-border use of the renminbi, and offering more convenient foreign exchange management.

"The promulgation of the Qianhai Plan will foster Hong Kong-Shenzhen co-operation at a higher level under which the two cities can serve as 'dual engines' to drive development in the Greater Bay Area," Mrs Lam was cited as saying in a press release from the Hong Kong government.

Mrs Lam took a one-day trip to Shenzhen on Monday for high-level meetings, according to the government.