The new president said the inquiry would include "those registered to vote in two states, those who are illegal", the BBC wrote.
Mr. Trump also said the probe would focus on "those registered to vote who are dead (and many for a long time)".
Read alsoReuters: Trump clears way for controversial oil pipelinesHe has alleged that up to five million illegal votes were cast for Hillary Clinton, but has offered no evidence.
"Depending on results, we will strengthen up voting procedures!" Mr. Trump said of his planned inquiry.
I will be asking for a major investigation into VOTER FRAUD, including those registered to vote in two states, those who are illegal and....
— Donald J. Trump (@realDonaldTrump) January 25, 2017
even, those registered to vote who are dead (and many for a long time). Depending on results, we will strengthen up voting procedures!
— Donald J. Trump (@realDonaldTrump) January 25, 2017
