In her maiden policy speech, Hong Kong's Chief Executive Carrie Lam on Wednesday warned the city faced "grave" challenges and must develop a diversified and high value economy, unveiling a mix of housing and tax relief policies to raise competitiveness.

Hong Kong, now among the world's most costly cities, has battled rising income inequality, the slow implementation of marquee public projects, political tensions with mainland China, and a slide in regional competitiveness.

"In the face of competition from other economies as well as the rise of protectionism in recent years, Hong Kong is facing increasingly grave challenges. We must develop a high value-added and diversified economy," Lam said.