Visiting U.S. Secretary of State Hillary Clinton said on Tuesday that Iran will face the "most significant" sanctions starting from Wednesday, a day before the UN Security Council was expected to vote on the issue.

"I think it's fair to say those are the most significant sanctions that Iran has faced and the unity of the international community is very important," Clinton said during a joint press conference with Ecuadorian President Rafael Correa.

Clinton said she will not predict the results of the voting at the Security Council on Wednesday, because in previous opportunities the United States have not achieved consensus for harsher sanctions against the Iranian nuclear program.

Clinton arrived in Quito on Tuesday. She will also visit Colombia and Barbados.