Hong Kong police will carry out what sources have described as a "major exercise" today to prepare for possible chaos caused by Occupy Central.
Force insiders also told the South China Morning Post that extensive upgrades had been made and extra equipment introduced at the Police College in Aberdeen to ensure it could cope with any eventuality.
"Numerous" platoons from the Police Tactical Unit and a large number of other formations will take part in the Aberdeen exercise.
Meanwhile, some 4,000 officers will be deployed to maintain order during the annual July 1 march, as part of their preparations for Occupy Central.
Watch: Hong Kong police stage ‘major exercise’ in preparation for Occupy Central
The Police College will be turned into a temporary detention centre for the first time during the operation, according to police sources.
The move is understood to have been given the green light after police sought approval from the Department of Justice.
But one source said the college - which is situated next to Ocean Park - would only be used to detain marchers in the event of mass arrests. Otherwise they would be held at police stations.
"The Police College has been chosen because it is our own facility with catering services and proper security measures are in place," the source said.
"Detainees might be kept in an indoor training compound where they [would be] separated by barricades and guarded by our officers," the source said.
He said police would deploy about 4,000 officers from the Police Tactical Unit, traffic divisions, patrol sub-units and emergency units along with auxiliary police officers.
It is understood that the number will not include any officers from the crime squad or the force's intelligence unit.
The Civil Human Rights Front will hold a protest on July 1 to argue for universal suffrage. Supporters will march from Victoria Park in Causeway Bay to the Chater Road pedestrian precinct in Central. Organisers expect 100,000 people to take part.
Another police source said the operation was necessary in the event that radical activists refused to leave after the gathering in Chater Road and went on to cause disruption in Central.
The source added that July 1 would be considered as preparation for a massive operation to handle Occupy Central, codenamed Solarpeak. "But the Solarpeak operation will involve other agencies such as the Security Bureau," the source added.
Occupy Central will give the government time to respond to the results of an unofficial referendum on universal suffrage before deciding whether to blockade streets in a campaign of civil disobedience.
By 5pm yesterday, 734,737 people had cast votes to pick their preferred proposal from a shortlist of three reform plans, all of which want the public to be able to nominate candidates for the 2017 election of chief executive.