Democratic US presidential candiate Hillary Clinton (C) celebrates with New York US Rep. Carolyn Maloney (L), Rep Gregory Meeks (2nd L), Rep. Eliot Engel and former New York City Mayor David Dinkins (R) at her New York presidential primary night rally in the Manhattan borough of New York City, US, April 19, 2016. [Photo/Agencies]

Clinton's win in New York followed some of the most heated personal exchanges of her campaign against Sanders, a US senator from Vermont who had won seven of the last eight state-by-state nominating contests.

The New York victory will expand Clinton's lead of 244 pledged delegates over Sanders, and make it nearly impossible for him to overcome the deficit and capture the 2,383 convention delegates needed for the nomination under Democratic rules that allocate delegates proportionally based on each state's result.

The voting in New York was marred by irregularities, including more than 125,000 people missing from New York City voter rolls. The city has roughly 4 million voters considered active for the primaries.

New York City Comptroller Scott Stringer ordered an audit of the city elections board after it confirmed the names had been removed from voter rolls. He told the board in a letter it was "consistently disorganized, chaotic and inefficient."

"It is absurd that in Brooklyn, New York, where I was born actually, tens of thousands of people as I understand it have been purged from the voting rolls," Sanders told supporters at a rally in State College, Pennsylvania.