In a statement, the Organization for Security and Cooperation in Europe (OSCE) says the election did not meet standards for a free and fair vote. That assessment was delivered in Minsk by U.S. Representative Alcee Hastings, the special coordinator of the OSCE's 500-member observer mission in Belarus.
In Brussels, European Commission spokeswoman Emma Udwin said the bloc will probably impose some sanctions on Belarus in protest at the conduct of the election.
"It is now really very likely that some action will be taken, following up what the council [of EU foreign ministers] said in both November and January, that ministers stood ready to take further restrictive measures if the elections turned out not to be free and fair," Udwin said.
The pan-European rights body the Council of Europe described the poll as a "farce" and said President Alyaksandr Lukashenka "is a president with a tainted mandate."
But Russia's Foreign Ministry said the vote was fair and that the results should be respected.
Vladimir Rushailo, the head of an observer mission from the Commonwealth of Independent States, concluded that, despite some technical violations, the election took place within the requirements of Belarusian law.
Click on the image to view a photo gallery of election-day events in Belarus.
THE BELARUS ELECTION: To view a complete archive of RFE/RL's coverage of the March 19 presidential election, click here.
To read and listen to RFE/RL's Belarus Service's coverage of the vote in Belarusian, click here.