Activists Benny Tai (left) and Chu Yiuming attend a news conference in Hong Kong on Tuesday. [Photo/Agencies]

Three people who conceived the "Occupy Central" campaign in Hong Kong turned themselves in on Wednesday afternoon, Hong Kong media reported.

Starting from 3:00 pm, the three founders of the campaign began appearing at the Central Police Station and admitted to "participating in the unsanctioned mass protest."

Benny Tai Yiu-ting, a law professor at the University of Hong Kong, proposed 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, they called for protesters to assemble to launch the "Occupy Central" movement.

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

Legal experts in Hong Kong said the men may face multiple charges and imprisonment for up to?five years if convicted.

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.