Screen grabs posted online by Twitter users included an alert reading "Heil President Donald Trump!" among a series that ran on Saturday, which was April Fool's Day.
The New York Post apologised early on Sunday hours after its app was apparently hacked with what was reported to be alerts about President Donald Trump.
"The push alert system for our mobile app was compromised this evening. Please accept our apologies," the newspaper said on Twitter several hours after the alerts went out.
