Two academics and a pastor who conceived the "Occupy Central" campaign in Hong Kong will turn themselves in today.

Legal experts in the city said the men may face multiple charges and imprisonment for five years if convicted.

Benny Tai Yiu-ting, a law professor at the University of Hong Kong, put forward the idea of an occupation protest in January 2013 to push the opposition's agenda on political reform.

He was soon joined by Chan Kin-man, a Chinese University of Hong Kong sociologist, and the Reverend Chu Yiu-ming.

After midnight on Sept 28, the three founders of the campaign called for protesters to assemble to launch the "Occupy Central" movement.

The first road was blockaded about 12 hours later outside the government headquarters.

More than nine weeks later, the three men told reporters that they will surrender on Wednesday. But they only admitted wrongdoing in relation to the regulation covering public meetings or gatherings stipulated under Hong Kong's public order ordinance.

Publicizing an illegal rally is liable to a fine of HK$10,000 ($1,290) and 12 months' imprisonment. Those who convene, organize and knowingly take part in such assemblies face imprisonment of up to five years if convicted.

But the three may also be charged with unlawful assembly, under section 18 of the public order ordinance, said Lawrence Ma Yan-kwok, a lawyer.

Under Hong Kong law, unlawful assembly occurs when three or more people assemble and conduct themselves in a disorderly manner, provoking anyone to commit a breach of the peace, or causing a person to fear so doing.

Ma speculated that the three might try to show remorse and argue their actions were "civil disobedience", but the city's High Court, in an earlier ruling on applications for injunctions, did not accept such an argument.

Albert Luk Wai-hung, also a lawyer, said the three could also be arrested for inciting others to commit offenses but that the situation will become clear only once police press charges.

At a news conference on Tuesday, the three men called on protesters to withdraw for safety reasons.

Tai said the latest protests have been more aggressive than the "Occupy Central" campaign anticipated. Chu also said the protesters have deviated from the proclaimed principle of "love and peace" they espoused months ago.

Hong Kong's Chief Executive, Leung Chun-ying, cast doubt on the three activists' influence on defiant protesters when he spoke at an Executive Council meeting on Tuesday. "After spending all this time plotting and organizing the 'Occupy Central' campaign, the three initiators can finally draw a conclusion - it's easy to invite any occupiers in, but hard to send anyone away. And they themselves have already left to live a normal life," he said.