About 2,000 police officers will fan out between Causeway Bay and Central tomorrow to monitor the city's first mass rally since the Occupy sit-ins, according to a police source. They are to act on any unlawful activity, such as illegal road occupation, that emerges during or after the march for "genuine universal suffrage" with organisers expecting a turnout of about 50,000 protesters. Police are also readying reinforcements to deploy in case of major unrest. They would include officers who were involved in the Solarpeak operation to deal with the 79-day Occupy democracy protests, the source said. Ahead of tomorrow's event, activists have hinted a sit-in may take place, similar to an overnight protest after last year's July 1 march that served as a rehearsal for Occupy. "Police will take appropriate and necessary enforcement actions in case of any unlawful act," the source said. He said most of the officers were from the crack Police Tactical Unit, traffic units, and patrol sub-units of Eastern, Wan Chai and Central police districts. Crime-squad officers are expected to be present along the route and at the protest gathering in the Chater Road pedestrian precinct, where the march ends. Even as the police appeared to have everything planned out, march organiser Civil Human Rights Front said it had recruited only 60 to 70 marshals as of yesterday to maintain order - short of the 100 police had required. But Tang Ping-keung, deputy regional commander of Hong Kong Island, said police would not stop the march if the organiser failed to reach the target, as long as measures could be implemented to ensure protesters proceeded in a safe and orderly way. "We will liaise with the organisers [and see] how those problems could be mediated," he said. Police have told the organiser to help officers call on participants to disperse at the end of the rally. However, Johnson Yeung Ching-yin, the organiser's deputy convenor and chief marshal of the march, said they were powerless to - and should not - stop or control what others planned to do afterwards. Yeung noted two pro-Beijing organisations were going to set up street booths along the route and reminded protesters not to be provoked. Front convenor Daisy Chan Sin-ying asked protesters to bring along their umbrellas to bolster the spirit of the "umbrella movement", which the Occupy protests were dubbed. "Umbrellas have represented our everyday persistence in demanding genuine universal suffrage," Chan said. She said the government had not shown any sincere willingness to offer concessions in the second round of political reform consultation, and hoped Hongkongers would show up at 1.30pm at Victoria Park to voice their calls for democracy.