Bloomberg, 67, a billionaire who founded the financial news agency Bloomberg LP, beat New York City Comptroller William Thompson Jr., 56, a Democrat. Bloomberg, a former Republican, no longer belongs to any party.

Local television channel NY1 said that with 95 percent of the ballots counted, Bloomberg attained 50 percent of the votes, while Thompson had 46 percent.

Bloomberg took the initiative in changing city law so he could run for a third four-year term. This has drawn fire from challenger Thompson.

Thompson has also criticized Bloomberg for spending a huge amount of money on his campaign. Bloomberg, the richest man in New York, is said to have spent more than $100 million on the most expensive self- financed campaign in U.S. history.

The incumbent mayor claims that he has overhauled New York City's educational system and that the security situation in the city has improved in the past eight years.