Image copyright AP Image caption Mass demonstrations have largely subsided in recent days in Hong Kong

Hong Kong's government has called off a meeting on Friday with student leaders of the pro-democracy movement.

Chief Secretary Carrie Lam said it would be "impossible to have a constructive dialogue" after protest leaders called for an increase in efforts to occupy main protest areas.

The protesters want a fully free vote in elections due to be held in 2017 for the post of chief executive.

Last week thousands of demonstrators paralysed parts of the city.

But mass demonstrations have largely subsided in recent days, although the barricades remain in place.

What happens next will largely depend on whether people do indeed rally once again to the cause, prolonging the political crisis, or whether the movement continues to dwindle of its own accord, the BBC's John Sudworth in Hong Kong reports.

'Cleaning up mess'

Hours before Ms Lam's announcement student leaders had asked for an escalation of those activities if concessions were not made by the government.

Image copyright AFP Image caption Chief Secretary Carrie Lam asked for the "illegal" occupations to stop

Image copyright Getty Images Image caption The protests have had a significant impact on businesses and shops in Hong Kong

Ms Lam accused them of "undermining trust" in the proposed talks.

"The dialogue cannot be deployed as an excuse to incite more people to join the protest," she said. "The illegal occupation activists must stop."

Pro-democracy leaders later urged the authorities to return to the negotiating table.

"The chaos was caused by the government. They are responsible for cleaning up the mess," Alex Chow, the president of the Hong Kong Federation of Students (HKFS), was quoted as saying by the AFP news agency.

Meanwhile, pro-democracy MPs in the former British colony threw their weight behind the protests by pledging to block key legislation.

Protesters occupied key parts of the Asian financial hub last week, after riot police used tear gas in a failed attempt to disperse the crowds.

Under Hong Kong's current system, the chief executive is elected by a 1,200-person committee that consists primarily of pro-Beijing groups.

In August, Beijing said it would allow a public vote in the 2017 elections. However, China wants all candidates to be approved by a similar committee - effectively giving it the ability to screen out candidates.

Hong Kong democracy timeline

1984: Britain and China sign an agreement where Hong Kong is guaranteed "a high degree of autonomy, except in foreign and defence affairs" for 50 years following the handover in 1997

June-July 2014: Pro-democracy activists hold an unofficial referendum on political reform and a large rally. This is followed by protests by pro-Beijing activists

31 August 2014: China says it will allow direct elections in 2017, but voters will only be able to choose from a list of pre-approved candidates. Activists stage protests

22 September 2014: Student groups launch a week-long boycott of classes in protest

28 September 2014: Occupy Central and student protests join forces and take over central Hong Kong

2 October 2014: Chief Executive CY Leung refuses demands for his resignation, offers talks with government. Student leaders later accept the offer

2017: Direct elections for chief executive due to take place

Q&A: Hong Kong's democracy controversy