They also said they know exactly where the 79-year-old Columban missionary is being held on a remote southern island in the Asian country.
The development comes five days after Fr Sinnott was abducted from his compound in Pagadian City on Mindanao island.
It is believed that the abductors responded to the revelation that Fr Sinnott's life was in danger without daily medication for his heart problems.
Major General Benjamin Dolorfino admitted today that his troops knew where Fr Sinnott was being held, but they were not going to be sent in to rescue him until all peaceful options were exhausted.
The military had previously said that a local pirate may have turned the priest over to a local leader of the Moro Islamic Liberation Front, a Muslim separatist rebel group.
However the MILF leadership has denied any of its commanders were involved, and insists it is helping to secure Fr Sinnott's release.
Meanwhile, the head of the Columban missionaries in the Philippines, Patrick O'Donoghue, denied media reports that the abductors had contacted the order.
