LONDON (Reuters) - Sadiq Khan was re-elected as London's mayor, final results showed on Saturday, helping to cement the Labour Party's commanding lead over the governing Conservatives in local polls ahead of Britain's national election later this year.

Khan's victory, his third in a row, was widely expected despite some public anger over knife crime and the Ultra Low Emission Zone (ULEZ), which charges drivers of older, more polluting vehicles a daily fee.

The Conservative candidate, Susan Hall, had been viewed by many as too divisive.

For Labour, London is the latest of several councils and mayoralties it has won in the local elections, which were held on Thursday, inflicting heavy losses on Prime Minister Rishi Sunak's Conservatives.

Opinion polls predict the party will win the next national election, propelling its leader Keir Starmer to power and ending 14 years of Conservative government in Britain.

Khan, 53, who became the first Muslim mayor of the British capital in 2016, has pledged to build more social housing and work with a future national Labour government to boost police capacity.

(Reporting by Sachin Ravikumar; Editing by Gareth Jones)