Authorities in Hong Kong have offered to hold talks with pro-democracy protesters who are continuing to occupy central areas of the southern Chinese city, pressing for political reforms.

Minutes before a midnight deadline set by the protesters for Hong Kong's chief executive Leung Chun-ying to resign passed, Leung said he would send his chief secretary to meet the demonstrators.

He said he had no intention of stepping down. The students had earlier on Thursday threatened to escalate their protests - including occupation of government buildings - unless Leung stepped down.

He warned the protesters of serious consequences if they chose to storm government buildings.

Notes from the field:  
Al Jazeera's Divya Gopalan

The centre of gravity of the protests has moved to the area right in front of the chief executive's and government offices. People are pouring in despite the fact that, or perhaps because, Friday is a working day after two days of public holidays.

Student protesters are calling for people to stay put until 8am in the morning when Leung Chun-ying, Hong Kong's chief executive, is supposed to arrive for work.

In a surprise move, just before his midnight deadline, Leung held a press conference. It was blasted through loudspeakers at the protests in front of his office. Leung said the government was open to dialogue, but warned of serious consequences if the protesters stormed government buildings. He was roundly booed.

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Al Jazeera's Divya Gopalan, reporting from Hong Kong, said Leung gave no time-frame for the talks.

She said that Leung's statement was played on loudspeakers to the protesters outside and was received with a lot of booing.

She noted that the crowd had become noisier since the speech. but there had been no attempts made so far to cross the barrier.

Thousands of protesters have been camping out in the main streets of the Chinese autonomous region for the past several days.

Police manned barricades at a nearby intersection, with protesters camped on the other side, huddled under umbrellas.

"It's too late for [Leung's] government to be accountable to the people, so we want a new one," May Tang, a 21-year-old student protester, told AP.

With the protests showing no signs of waning, Wang Yi, China's foreign minister, issued the warning to the US and other foreign countries not to interfere.

Reuters news agency, citing an official source, reported that Leung was willing to let the demonstrations go on for weeks if necessary.

Speaking in Washington, Wang said China would not tolerate "illegal acts that violate public order".

The People's Daily newspaper, the government's official newspaper, said in a commentary on Thursday that Beijing "fully trusts" Hong Kong's Leung, and that it is "very satisfied with his work".

The week-long street protests by thousands of demonstrators pressing for electoral reforms in Hong Kong are the biggest challenge to Beijing's authority since China took control of the former British colony in 1997.

The protests erupted after the Chinese government restricted who can run as the commercial hub's next chief executive, or leader, in elections scheduled for 2017.

'Columns of police'

Al Jazeera's Gopalan said police, who were criticised for being allegedly heavy handed with protesters, have largely remained in the background in recent days.

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"But on Thursday afternoon we saw columns of police hand carry riot gear and equipment into the compound after protesters stopped their vehicles from entering," she said.

"It seems they still have plenty of citizens on their side. Every now and then a vehicle will honk in support of the protesters, who will respond with loud cheers.

"The protesters have accused the police of using ambulances to ferry more colleagues and hight intensity riot gear. We have seen them search an ambulance that tried to enter: it was empty.

"But it is not just a case of protesters versus the police and officials here. We are starting to see cracks within the protest movement."

Our correspondent said a group tried to block the main highway that links the east and west of the island which would have greatly inconvenienced the public, who have been largely tolerant of the protests.

"There was a confrontation with other protesters, the majority I would say, who finally shouted and chanted for them to get off the road and let traffic pass," she said.

"It is hard to say which way these protests will go, but the police have made it clear that what they are doing is illegal and if the protesters do not comply with their warnings, they will take 'resolute action'.

"The protesters are well prepared, though, for any eventuality. They have been handing out home-made anti-riot gear, towels and other equipment to in case of tear gas and pepper spray.

"More impressively, they have been handing out leaflets on what to do if they are arrested, with a hotline number for legal advice."

Source: Al Jazeera and agencies