BEIJING - Chinese Premier Li Keqiang has set a to-do list for Hong Kong's chief executive-elect Carrie Lam, urging her to develop the economy, unite all sectors of society, and take the city to "a new level".

Li presented an official certificate of appointment to Lam on Tuesday (April 11). The 59-year-old will take over from Leung Chun Ying in July as Hong Kong's top leader.

"This is a very heavy responsibility," South China Morning Post (SCMP) quoted Li as telling Lam at Zhongnanhai, the central government's leadership compound in Beijing. "This is also the high hopes on the new administration from the central government and Hong Kong people," he said.

"The central government will support the Hong Kong SAR government to develop the economy and improve people's livelihood," Li added, referring to the Special Administrative Region.

The Chinese Premier announced his work plan last month, which includes turning Hong Kong, Macau and Guangdong province into a greater economic bay area.

Lam said she was honoured to receive the certificate of appointment from Li and reiterated her gratitude for the trust and support from Beijing, according to SCMP.

"I will fully implement the constitutional responsibility of the chief executive in the coming five years - not only be held accountable to the Hong Kong SAR government but also to the central government," she said.

Lam won 777 votes, or 67 per cent of the 1,163 valid votes cast by a largely pro-Beijing election committee on March 26.