LAGOS, Nigeria — Nigeria's president says he challenges a prominent critic to prove allegations of corruption and that he is training a death squad to kill enemies.

But President Goodluck Jonathan, in a letter posted on his special adviser's website Monday, did not address charges that he is shielding a party financier indicted for drug trafficking in the United States and that drug barons are influencing politicians.

Jonathan responded to allegations made by his former mentor and ex-President Olusegun Obasanjo.

Jonathan said he asked security agencies and the national human rights commission to investigate claims he is training an assassination squad.

And he demanded that Obasanjo provide facts about the "high corruption which you say stinks all around my administration."

Jonathan remained silent on Obasanjo's charge that he plans to run for re-election.