The additionof high-speed rail will strengthen the synergy effect among the three economic zones and create more opportunities, Lam said.

Lam thanked the support from central government authorities, the Guangdong provincial as well as the Shenzhen city governments.

She also expressed gratitude to the China Railway Corporation for providing the best arrangements on train scheduling, ticketing and finance to Hong Kong.

Welcoming the new cross-boundary infrastructure, Governor of Guangdong province Ma Xingrui called the commencement of service a "milestone", introducing a major boost for cooperation between Guangdong and Hong Kong.

Lu Dongfu, general manager of China Railway, said the XRL integrates the Hong Kong SAR into the nation's 25,000 km express rail network and serves as a bridge for closer integration between the city and the mainland.

High-speed rail opens a new chapter for Hong Kong's future and promises abundant opportunities, said Frederick Ma Si-hang, chairman of the MTR Corporation, the operator of the Hong Kong section of the XRL.

Lam and Ma Xingrui officiated at the ceremony in Hong Kong. Later they, together with other guests, went through Hong Kong and mainland boundary clearance procedures under the co-location arrangement, all at the West Kowloon Station.