The Hong Kong government will spend up to HK$10bn ($1.3bn) on subsidies to phase out old diesel commercial vehicles in a bid to improve the city’s appalling air quality, which has become a subject of growing concern among citizens and international companies.

The new measures, announced by Hong Kong chief executive Leung Chun-ying in his first policy address since becoming leader of the city of 7m in July, are designed to bolster public support for his embattled tenure.

Mr Leung, the city’s de facto mayor, has struggled since he took office last July to articulate his agenda for tackling the city’s high property prices, shortage of affordable public housing and poor air quality because he has had to fend off repeated controversies including an unsuccessful attempt to introduce a civics course in the city’s schools that extolled the virtues of Communist China.