The number of elephants in two wildlife sanctuaries in Tanzania has fallen by nearly 42 percent in just three years, a census showed on Tuesday, as poachers increasingly killed the animals for their tusks.

The census at the Selous Game Reserve and Mikumi National Park revealed elephant numbers had plunged to 43,552 in 2009 from 74,900 in 2006.

It was carried out by the east African country's wildlife authority, Tanzania Wildlife Research Institute, as part of a government plan to conserve wildlife.