Demonstrators in Hong Kong have set a deadline of Wednesday for the government to respond to demands for reforms, as protests enter a fifth day.
But in his first public comments since police fired tear gas at demonstrators, Hong Kong's chief executive Leung Chun-Ying called on protest leaders to "immediately" withdraw their followers from the streets.
"Occupy Central founders had said repeatedly that if the movement is getting out of control, they would call for it to stop," he said.
"I'm now asking them to fulfil the promise they made to society, and stop this campaign immediately."
But Occupy, the main group behind the last two days of street protests, rejected Mr Leung's demands and renewed its calls for him to step down.
"If Leung Chun-Ying announces his resignation, this occupation will be at least temporarily stopped in a short period of time, and we will decide on the next move," co-founder Chan Kin-Man told reporters.
"This would be a very important signal, then at least we know the government has changed their attitude and wants to solve this crisis," he said.
Some demonstrators have worn masks and resorted to umbrellas or plastic capes to protect themselves - prompting the phrase "umbrella revolution" to trend on social media.
However, in a shift of tactics, uniformed police looked on from behind barricades and have so far not intervened in the peaceful protest.
Sky's Asia Correspondent Mark Stone, on the scene, said the activists were "good natured but utterly driven".
On Sunday night, riot officers fire 87 rounds of tear gas after being charged by "violent protesters", with police saying 41 people had been injured.
Britain's Prime Minister David Cameron has told Sky News that he is "deeply concerned" about the situation in the former colony and hopes it can be resolved.
China, meanwhile, has warned the international community not to "interfere".
Officials called on the activists to leave peacefully on Monday but thousands remained camped on a normally busy road near government headquarters.
Organisers estimate as many as 80,000 people have taken to the streets since Friday.
With no imminent end in sight, China appears to have blocked photo-sharing site Instagram, suggesting authorities are worried about inspiring similar protests on the mainland.
Many shared photos of the demo have been hashtagged "Occupy Central".