no more than 24 hours at the latest.
according to article 85 of the criminal procedure law, when a public security organ detains a person, it must produce a detention permit. After detention, the detained person shall be immediately sent to the detention center for custody, and no later than twenty-four hours.
except in cases where it is impossible to notify or the notification of crimes suspected of endangering national security or terrorist activities may hinder the investigation, the family members of the detained person shall be notified within 24 hours after detention. After the circumstances that hinder the investigation disappear, the family members of the detained person shall be notified immediately. The public security organ shall interrogate the detained person within 24 hours after detention. When it is found that it should not be detained, it must be released immediately and issued with a release certificate.
Extended information:
Relevant requirements of criminal proceedings stipulate that:
1. The people's procuratorate shall make a decision on whether to approve or disapprove the arrest within seven days after receiving a letter of approval from the public security organ.
2. If the people's procuratorate does not approve the arrest, the public security organ shall release it immediately after receiving the notice and notify the people's procuratorate of the implementation in time. For those who need to continue the investigation and meet the conditions of obtaining a bail pending trial or residential surveillance, they shall be released on bail pending trial or residential surveillance according to law.
3. If the public security organ thinks there is something wrong with the decision of the people's procuratorate not to approve the arrest, it may request reconsideration, but the detained person must be released immediately. If the opinion is not accepted, it may be submitted to the people's procuratorate at the next higher level for review.
Central People's Government-Criminal Procedure Law