Hong Kong's legislature has formally withdrawn a controversial extradition bill that has sparked months of unrest, the BBC reports.

The bill - which would have allowed for criminal suspects to be extradited to mainland China - prompted outrage when it was introduced in April.

Hundreds of thousands of people took to the streets and the bill was eventually suspended.

But protesters have continued regular demonstrations, which spiralled into a wider pro-democracy movement.

It is the worst crisis for Hong Kong since the former British colony was handed back to China in 1997.

It has also presented a serious challenge to China's leaders in Beijing, who have painted the demonstrators as dangerous separatists and accused foreign powers of backing them.

The proposed bill would have allowed for Hong Kong to extradite criminal suspects to places it does not have an extradition treaty with, including mainland China, Taiwan and Macau.

Critics of the planned law had feared extradition to mainland China could subject people to arbitrary detention and unfair trials.