Protest organisers say the Hong Kong police are trying to block Wednesday's Article 23 rally outside Legco by limiting the number of participants to just 6,000.
The Civil Human Rights Front plans to mobilise at least 50,000 protesters outside the Legco building when the anti-subversion bill is put to a vote on Wednesday. If it goes ahead as planned, the debate is expected to last for several days.
Emerging from talks with the police on the protest details yesterday, the Front's spokesman, Lee Cheuk-yan, said he was informed that the turnout should not exceed 6,000.
Police had earlier said the area could accommodate 10,000 people at most.
The police, however, stopped short of making the 6,000 figure a condition before issuing the so-called letter of no objection.
They also promised to invoke contingency plans to accommodate more people should they show up, according to Mr Lee.
But the veteran protest organiser accused the police of trying to minimise the turnout.
'Obviously, the police want to create the impression that the opposition to the bill is not as solid as the 500,000-strong protest last Tuesday,' he said.
'We urge people to come to mount pressure on the pro-government lawmakers. Even if we can't have the strong show of opposition we had on July 1, we can have 50,000 people protesting day after day until the end of the vote.'
With Article 23 supporters also planning street campaigns in the area, Mr Lee said he had demanded that the two groups be kept as far apart as possible to avoid clashes between them.