US presidential hopeful Senator Bernie Sanders on Wednesday criticized low Internet speeds for users in the United States, drawing a comparison between America and Romania.

According to Sanders, residents of Romania enjoy much faster Internet than American citizens. This is unacceptable, Sanders states, and must be changed.

"High-speed Internet access is no longer a luxury. It's crucial for rural America to be connected and do business with the rest of the world," the self-described democratic socialist said on his campaign Twitter page.

"Today, people living in Bucharest, Romania, have access to much faster Internet than most of the US," he later tweeted, adding, "that's unacceptable and must change," without explaining why he chose Romania for comparison.

Sanders is currently in second place, behind former Secretary of State Hillary Clinton, in the Democratic presidential race.

The Senator has distinguished his candidacy by refusing to set up a Super PAC (political action committee) for his campaign, stressing that his campaign is not only about electing a president, it "is about transforming America," while addressing supporters in his home state of Vermont.

Sanders is Clinton's only rival, and trails behind the former first lady in polling and delegates.