One of the of the hardest-hit prefectures, Miyagi, estimates that the deaths will top 15,000 in that region alone, police spokesman Hitoshi Sugawara said.
Police in other devastated areas declined to estimate eventual tolls, but said the confirmed deaths in their areas already number nearly 3,400.
The National Police Agency said the overall number of bodies collected so far stood at 8,649, while 12,877 people have been listed as missing.
It is possible those two lists have overlap, and that some unidentified bodies in the tally of deaths may match names on the missing list once their identities are confirmed.
An eventual death toll also is complicated by the fact that the tsunami likely swept many bodies out to sea, as it did in the 2004 Indian Ocean tsunami, when many of the dead were never found. Also, some missing people may have been out of the region at the time of the disasters but have not yet contacted relatives or authorities.
In addition to Miyagi's estimate of more than 15,000 dead, police confirmed nearly 3,400 deaths in Iwate, Fukushima, Ibaraki, Aomori and Chiba provinces, as well as seven dead in Tokyo.
