Hong Kong's top official doubled down on a contentious plan to allow extraditions to China on Monday, one day after hundreds of thousands of protesters took to the streets in one of the biggest demonstrations to shake the former British colony in years.

Carrie Lam, the territory's chief executive, ignored calls for her resignation and reiterated the need for the legislation.

The rally highlights increasing public anger against the government's proposal to seek legal changes to allow people in Hong Kong to be extradited to places with which it has no such agreement — including China.

Flanked by the secretaries for justice and security on Monday, Lam stressed safeguards built into the legislation to prevent human rights abuses and said she will continue in her job. She also lauded those who participated in the march and said it shows that Hong Kong's "rights and freedoms are as robust as ever."

Police estimated about 240,000 people marched Sunday at the peak of the protest which saw crowds overflow a city thoroughfare. Organizers, meanwhile, claimed that slightly more than one million people participated. The event rivaled a 2003 demonstration when a reported 500,000 people protested proposed security legislation.

Marchers shouted slogans and held up signs demanding the government withdraw the proposal and for Lam to quit.

It came as concerns have increased that Hong Kong's rights and freedoms are eroding under what is perceived as increased efforts by the central government in Beijing to increase its influence.

Hong Kong, which on July 1 marks 22 years since Britain handed the territory back to China, was guaranteed a high degree of autonomy as a Special Administrative Region under a "one country, two systems" framework that was to remain unchanged for at least 50 years.