Hong Kong's government Wednesday announced a roadmap for leadership elections which offered no concessions to the city's democracy camp -- prompting opposition lawmakers to walk out of the plan's unveiling.

Deputy leader Carrie Lam said the first-ever public vote for the post of chief executive in 2017 would be held in "strict compliance" with a ruling by China's National People's Congress last August.

That ruling stated that candidates for chief executive must first be approved by a loyalist committee -- a decision that sparked more than two months of street protests towards the end of last year.