Iran's semiofficial Fars news agency says 40 Iranian media outlets have added $600,000 to a bounty for the killing of Indian-born author Salman Rushdie.
Fars, which itself earmarked $30,000, published the list of the news outlets on February 22.
The move comes 27 years after the leader of Iran's 1979 Islamic Revolution, the late Ayatollah Ruhollah Khomeini, issued a fatwa, or religious edict, calling on Muslims to kill Rushdie after his book The Satanic Verses was declared blasphemous against Islam.
An Iranian religious organization offered a $2.7 million reward to anyone carrying out the fatwa and in 2012 it increased the amount to $3.3 million.
After the fatwa was issued, Rushdie lived in Britain under police protection and went into hiding for several years.
Other people involved in the book's publication were attacked.
The religious edict provoked an international outcry and caused Britain to sever diplomatic relations with Iran.