The matter was discovered when security agencies attempted to trace them, but couldn't find them at the location they had mentioned in their C-forms.
All Pakistanis have to fill the C-form while entering India.
High alert in Mumbai
Maharashtra ATS leading manhunt
Police said none of the 26, who vanished two-three weeks ago, had provided accurate details in their C-forms about who they had come to meet.
The Maharashtra Anti-Terrorism Squad, which is supervising the manhunt, has sent forces to all lodges in and around Mumbai.
There are reports the Indian Mujahideen had conducted reconnaissance in Mumbai in recent months.